It’s machined I just added a paint dot

Weak valvesprings?

Pulled from the Cudas 318, they are the same heads actually. It spun to 6000 just fine when I took it off of the road. Comp upgraded springs.

I'm trying to think of something constructive. I think I would do a compression test & tho since the marks ain't off you should be good there but if it does show OK then the long block is OK & all that is left is ignition or mixture issue (vac leak).

The distributor rotor position looks skeptic, I am going to reset it along with a new distributor and try again. If that doesn't cut it, i'm grabbing the 600 AFB from the Dart and sticking it on there.

With the magnet dead even with a tooth the rotor should be at the CW edge of the cap terminal or even a bit "inward" from that CW "edge" cuz Rotor Phasing from vac adv & only vac adv will shift it back CCW (on a SB). The cap terminal is .214" wide & the rotor blade is .244" wide so you have a fair amt of leeway there. Also there is the radial distance between the rotor blade tip & the cap terminals & those 2 "air distances" add up together & if that total distance is greater than what the voltage can jump then it will miss. there is a longer rotor available (or make your own) but if the circumferential RP distance (around the arc) is good then you are likely fine. decades ago my mentor from the early 60's had a pontiac (iirc) & it would not go past a certain speed (not sure if it was missing or not) just a family car & they scoped the ign & no issue & he finally got so frustrated that he was gonna blow it up! so he revved it high under the hood & THEN he saw it, the FUEL FILTER was going almost dry/mostly clogged! New filter=all good!

Plugged exhaust?

I'd bet the valves are not closing completely when rpms go above 3500. I use adjustable rockers on every Mopar engine I mess with. I also set the valves at a zero lash and have yet to experience valve float. I have had stock bottom end 360's rev to 7400 rpms with no issues or valve float. I feel that when you push the lifter plunger down you allow the lifters to over pump up when running. My father was a big performance engine builder back in the 60's and 70's and taught me this early on.

I have a set of 273 adjustable rockers, but I do not have all of the spacers and shims unfortunately.

I measured the pushrod length upon assembly and determined that it had sufficient preload with the stock rockers and pushrods.

You say the original engine did the same thing? I'd be looking at things that you reused first instead of any replaced component or engine mechanicals.

Have you tried disconnecting the tach yet?

Engine isn't back together yet. Gaskets come in on Monday.

No improvement with a different timing set, verified straight up with feeler gauges, and a known good distributor, new cap & rotor.

Coil next, remove the tach and swap carbs if that doesn’t work..saga continues!

So I’m guessing you didn’t degree the cam in.

Nope. There's no reason why it shouldn't run fine installed dot-dot with two different timing gear sets.

Unless the grind on the cam is off.

I've got an entire kit to degree the cam with the heads on the motor. If you don't mind the shipping I can send it down to you.

Ran just fine in my 318...it's the same cam the 'Cuda had in it before the Hemi swap.

I agree but how far off does it have to be to be THIS bad?
A loss at high rpm would mean the cam would have to be WAAAAY advanced, right?

I had a 318 in a 74 Duster that was an absolute PIG out of the hole. It would not even peel out on gravel. It ran smooth as glass, quiet and nice. I swapped distributors, carburetors, spark boxes, I cranked the static timing to the moon...nothing made any difference worth mentioning. I pulled the timing cover to see that the cam sprocket was 2 teeth off the mark retarded ! I replaced the set since the chain had slop. Once back together, it would peel out easily on pavement and ran just as smooth as before.

Forget cam timing, it may end up being a fuel issue....

I rechecked the float heights and they are in spec for what edelbrock calls for. I can take it from a sustained idle right to 3500-4000rpm and it immediately misses. I don't believe that is a fuel volume issue, pressure is good.

I also ran shop air over all four venturis, they all seem to be flowing well.