I am approaching a point in which I am considering redoing the entire wiring system in my Demon. It currently has a mixture of factory, CrackedBack’s, MSD, other parts brands wiring and my wiring. So none of the factory ignition wiring is used nor is the voltage regulator or alternator wiring is used. I have two BlueSea fuse boxes one is battery power fed and is feeding gauge lights, MSD, water pump, cooling fans, fuel pump and the other one is 12v keyed fed from the original radio power feed and runs the Dakota digital controller, and a couple other small item feeds. I really am not sure I want to cut the wires out of the factory harnesses as they are in good shape and intact currently. So I’m looking for input and ideas. I do have an engine harness from another car I would be totally cool with cutting up (72 Dart).

In a race car, I wouldn't use one piece of a 50 year old wiring harness. Take it all out, and start over.

Bet you could save 5 or more lbs if you took out all the old stuff no longer being used!

when i made a list of parts for the dart i had a wiring kit, as the budget changed i didn't buy one.......so after i exploded the coil got a new painless kit

Why not remove all of the stock harnesses into the engine compartment from the dash to run the engine and remove the stock harness up to the dash and use the stock wiring harness to the tail lights and head lights and wire them to the head light switch like stock with one 12v wire from a race switch panel?

This is exactly the info I’m looking for.

Speedway sells some nice,reasonably priced wiring kits.

So is there wiring aside from the alt, coil, voltage regulator, and sending units in the engine harness that I’m missing? I’m trying to figure out if I can pull that whole harness with no issues.

That's the way my Barracuda has been forever. Stock headlight switch with dimmer on the floor, turn signals work, brake lights would work if I plugged in the switch. I try to keep all the marker lights working. Tail lights come on when the fuel pump is running but a resistor reduces the brightness somewhat. Horn switch works through what's left of the factory harness as well. Later race oriented hardware on new wiring.

I don't think you missed any of those circuits except the horn in the engine harness along with the headlights and front turn signals The wiper motor harness and back up lights are in separate harnesses also

It is sans wipers, blower motor and the horns are long gone. The lights are on a separate harness aren't they?

We almost had a fire in the pits due to aged wiring and with all the extras added on to the stock wiring it was a mess. I also wanted the Challenger to remain street legal so I used 2 Painless systems. The std one for all the std stuff and the race one for the Ign, fuel pump(s), water pump, line lock and fans, there are also plenty spare ccts for other stuff. I also ran all the wires through the inside and under the front fenders for a clean engine bay. Turned out well, I have working interior, foot well and trunk lighting. I also changed just about everything to LED's IIRC it's only the H/L's that aren't

This is what I did, even before I switched to EFI. My factory wiring only runs the lights and wipers, that's it. Actually I do still use the key to power on the ECU but I have a starter button to start the car. Anything engine related is run by the EFI now but it uses to be a switch panel.

Yes they are
Most of the Mopar cars I've work on made after 1962 have four separate wiring harnesses in the engine compartment connected to the bulkhead junction block.