Installing a painless wiring system

You will never regret going with new harnesses. No way I would put a used harness in a new build. I tried to cheap out and wound up buying it all anyway, only a lot of swear words later. Classic and year one have regular sales and you can get the M&H stuff fairly reasonable. It is good quality. The big harnesses are reasonable priced, but they seem to gouge you on the smaller harnesses. Seems like the transmission harness with three wires was almost as much as the underhood harness which is a lot larger.