Which engine harness do I need?

[64stpside]

I'm going through the most rigged up wiring job I've ever seen in my 64 and someone bought a non-factory style ignition switch and wired it up, bypassing the factory ignition circuit. Thank god they didn't cut up the factory ignition switch plug. They truck has a 305 V8. I'm missing the engine harness under the hood. I assume the V8 harness is what I need but because the engine is a later model, I wasn't sure if it made a difference, v8 vs straight 6, being the connections at the starter and distributor (HEI) are different anyway from the factory connections, and i'll probably have to modify the connections anyway.
I want to get a factory ignition switch back in there being it sends power to other circuits.
Also, does anyone have a extra engine harness they would sell me?