Painless wiring???
I think the reason for the Chevy wire colors and connections is the whole street rod/350 Chevy bs. Because they (street rodders)would use as much of the engine donor car as possible. Painless offers an add on that gives an additional 8 keyed circuits. I used one of these to wire the 12 volt on my teardrop trailer, and just wired a toggle switch in place of the ignition switch wire.