If you don't have, I'd download both the 69 and 70 shop manuals here. I'm pretty sure 68-9 is very close
http://www.forabodiesonly.com/mopar/showthread.php?p=1970088491
I would unplug the ignition switch, unhook the coil, and hook up the battery. See if the ignition "run" wire right at the ign sw has power. This will confirm you have some sort of feedback
Unhook the field wire on the alternator and see if it has power under the above condition. It "should."
Unhook the coil and take a good look at what is hooked to the ballast resistor. WHAT do you have for an ignition system?
There is just NOT very much in the way of "stuff" going through the bulkhead, that is, you can eliminate much of it
Headlight high / low beam, so you can shut off the lights and that is dead
Turn signals, same deal. etc etc. Eliminate one circuit at a time
Take your meter/ light and draw out a diagram of the bulkhead. Map out which terminals are "hot" with everything in the car turned off.
This MAY be a problem in the under dash harness. You MAY have two or more wires melted together.
Another approach you could take is to SPLIT the problem into the engine bay --- or --- the interior
Pull all bulkhead connectors off in the engine bay
You will now have NO power into the car, because the battery feed (fuse link) is disconnected. Identify the fuse link connection. Since you have a damaged harness, you can "rob" a spade out of that bulkhead and plug only the one spade into the fuse link terminal in the bulkhead, and run a clip lead to the battery. Now you power back into the car, but you do NOT have any of the engine bay harness
Now see (with key off) if the "ignition run" or the "bypass" (ign2) wire is hot. If not your problem is in the engine bay.
