Underhood wiring replacement

[gable74]

So after spending a few days with my new ride I have decided the first project will be to clean up the engine bay wiring. Over the past 40+ years its seen its share of splices and add-ons. This truck was an original T60 and TP2 truck so I would like to track down the correct wiring for those as well. What I am looking for is some suggestions on a good resource for the harnesses. I would like to replace the wiring for everything under the hood all the way back to and including the connector on the firewall. It doesnt have to be NOS stuff or original but at least look period correct. Any suggestions? Phase two will be the mess of wires in the cab.

Thanks,
Jimmie