Wiring is one of those things that also require some talent. Sure, you can get some butt splices and black tape and patch in a piece to replace a frayed section, Y3, but a 38-yr old+ truck that you sink some serious money into and then expect to drive and perform well.....especially after we have become accustomed to fuel injection and disc brakes and cold AC....that truck deserves a decent wiring system.
Check out
www.wiringharness.com. They go by the name M&H Fabricators. Wes, at Classic Heartbeat (a site vendor) got me a good price on a buncha harnesses for my truck. You can PM him and see what he can do.
Even though my truck didn't have any electrical issues when I tore it down, the wiring came out and I got new harnesses because I don't want see it go up in smoke for want of a $200 harness...and that was the most expensive one.....if my memory is correct.