I rewired my ‘68 a while ago using a Painless harness. The only trouble I had was that the heater fan didn’t work. Of course as with all 02 projects, it is still a work in progress. ?
I drew up a (nearly) complete set of wiring diagrams and will try to get that and a parts list posted this weekend. Also, because it is a ‘68, it is much simpler than the later models and you will have to work out the missing circuits. It will at least give you a place to start if you are interested in going that route.