Here are a couple companies that will make a new harness for you. It would be a lot cheaper to do it yourself one wire at a time as you said. There can't be more than 8 or 9 circuits on that truck.
Complete reproduction wiring harness for all makes and models
YNZ Yesterday's Parts
http://www.ynzyesterdaysparts.com/909-798-1498
Wiring harnesses for all years, all makes and models
Rhode Island Wiring Service, Inc.
567 Liberty Lane, PO Box 434
West Kingston, RI 02892
(401) 789-1955
http://www.riwire.com/
