I have an engine that I recently rebuilt that has not been fired up yet. I would have liked to have just put it in the car and did the break-in that way but I have a new set of TTI's so I don't want to break the engine in with them on it and screw up the coating. I also thought about putting an old set of headers or manifolds on, installing the engine in the car (going from underneath), doing the break-in and then dropping it back out after the break-in to swap on the TTI's but I don't really feel like doing all that extra work. I had been looking for a used engine run stand locally for sale for several months but I wasn't able to find one and I don't want to spring for a new one as this is the one and only time I will have a need for it. So, I was trying to think of other ways to do this and was looking at my engine (with transmission attached to it) mounted to the k-frame and sitting on a dolly I made out of a heavy duty pallet with casters on it. It got me wondering if I were to secure the k-frame to the pallet using the k-frame bolt holes and put some old exhaust manifolds on it, could I do the break-in on the dolly? Has anyone ever done something like this?

No reason that won't work as long as you has coolant flow.

Yes can be. But you'd need to rig/hook-up all that's needed to fire up & monitor during break in.
Wiring, coolant, ignition, gauges, among others.
If you monitor fuel mixture really well while in car, burning off exhaust won't be a problem (extreme exhaust temps).
Lean fuel mixtures during break in will cause that.
Once has TTI's glowing red once cause of lean condition.
Keep the mixture towards the rich side will help.
Just my 2cents here.
Best to you.

I would add some kind of mufflers so you can listen for any weird noises.
And if you don't have enough timing in it, the exhaust manifolds/headers will get REALLY hot.
Seal the trans tailshaft (cup or spare yoke) to keep the ATF in, I think.

You're only going to be running the engine and possibly breaking the Cam in. The engine needs to be under a load to seat the rings

Put the [censored] in and run it!!!!!

I build and install lots of engines. My plans are to build a run in stand using a k member. My plan is to build a removable front section with the radiator and controls. I’ll just remove that part and install the engine from the bottom complete. That way I can test for coolant and power steering leaks.

I have ALWAYS pre-run my engines before final installation. It doesn't take anything elaborate. I used to start engines sitting on an old truck tire. The only precaution is to make sure it doesn't roll over. Done it many times without any issues. Your proposed set-up will work okay too, given a few precautions.

I think it is important to run the engine up to temp a few times before that final install. I check for any leaks, break the cam in, catch any mechanical issues, etc. And I wait until after the pre-run to paint the thing in case something needs unbuttoned.

There is plenty of time to 'seat' the rings after it's up and running in the car. I have never had an issue after install doing it this way.

Of course, this is not the only way to do it. But has ALWAYS worked for me.

Except how to use the starter. All my cars are manuals, so not an issue, for an automatic though.

Visited the shop of another Mopar guy here in town a few years ago and he had the stripped down shell of the front half of a Valiant (?) set up on a heavy duty metal shop table used for a run stand. It was just the firewall forward with the two frame rails, the k-frame, and the rad support. Wiring and dash was still there and you would set the engine on the k-frame and hook the hoses up to the radiator and wire it to make it run. I can't remember what it had for a fuel supply, but most likely a gas jug on the floor with a rubber hose plumbed from it to the fuel pump. It was pretty creative and likely did not cost as much as a real run-in test stand.

Just buckle up the tranny with the cooler lines looped. No biggy. Besides, it helps to steady the engine.

O.K. I will set-up a radiator and loop the trans. coolant lines. Still have to fill the trans. with fluid. What electrical things do I need to connect to fire it up (besides the obvious like the starter, distributor, ecu and coil)? Do I need a complete engine harness hooked up to fire it up?

Why do you need to loop the trans lines if the trans doesn't pump in park? Just curious. But if you fill the trans you will need to plug the tail shaft.

you could add an alternator and voltage regulator, thereby insuring the battery used would continuously supply a 12 volt supply to the ignition system used.
when some systems get below 10-11 volts, they can misfire, causing issues with the break in, unless you plan on doing the break in using 10 minutes or so segments. [recharging the battery between segments]
the only other engine harness items that i can think of that are factory supplied, [other than AC] are the electrical oil pressure and water temperature indicators. i'm assuming [and we all know what THAT means ] you will be monitoring those items with a set of gauges of your choice. mechanical gauges need nothing more than hooking to the appropriate supply outlets on the engine, while electrical gauges will require a 12v source, a ground, and a sending unit wiring harness for each gauge being in use.

Yeah, if the OP is doing a body-drop installation, might as well build out the accessories.
It's more convenient to check that stuff before installation anyway.
Wouldn't hang a fan on it, though - just use a room fan for the radiator. Safer for any poking around & setting timing.
I'd run mech gauges.

It can still move enough fluid to make a mess. Looping the cooler inlet and outlet is just a good precaution.

You really only need the ignition powered to run it along with the starter wiring. And that hook up will depend on what ignition you are running. But no matter what ignition you have, it is a simple wire or two. I use the black lead on some jumper cables for the heavy ground for the starter. You will likely need the alternator on it to drive the water pump. But you don't have to hook it up if you don't want to. Running the engine will draw very little juice. The only real draw will be the starter when cranking.

Personally, I do not power up the alternator during pre runs. Just more wiring to mess with and the outside chance of something going to ground when you don't want it to. If you are concerned about battery voltage when running dead loss, just hook up a battery charger while it's running. That's what I do. I just want the bare necessities during pre runs. I usually just use jumper wires for the ignition hook up and the starter wires for the starter. And I just hook and unhook the power jumper wire to the ignition for the on/off switch. Simple and fool proof.

A mechanical oil gauge is a must. I just have one on a short brass tube or hose. No need to mount it anywhere. A temp gauge is optional IF you have a temp gun which I like to have there anyway.

Do you have a priming rod?

Yes, I do have a priming rod. I've primed it already but plan on doing it again just prior to start-up.

I've ran and broke in several new cams in Mopar SB that I had rebuilt by using 4x4 under the front of the oil pan and under the front of the 4 speed tranny, I would hook up a complete stock exhaust system to the mufflers with no tail pipe and run them until they got up to a little over 200F on a mechanical water temp gauge and then shut them off and let them sit to cool down until they were below 160 F and then run them again until I got 30 minutes total run time at or above 1500 RPM, sometimes, depending on the time of the year, I would have to run them 2 or sometimes up to four times to get the 30 minutes total run time.
I would use a stock 1970 SB radiator without a fan and no alternator, one short belt that I could force onto both pulleys that would slip a little but would spin the water pump pulley fast enough to circulate the water with no thermostat
i did 4 or 5 different motors that way
I wouldn't try that on BB or Hemi motors, I would break them in the cars they went into or on the engine dyno testing and tuning them