I would purchase a harness made for the specific vehicle with all the wires the correct length and nothing left over for things you don't have. The one sold by Summit looks to be around $700 which is about the same as the specialty places.
YNZ Yesterday's Parts Complete reproduction wiring harness for all makes and models
http://www.ynzyesterdaysparts.com/909-798-1498
Rhode Island Wiring Service, Inc. Wiring harnesses for all years, all makes and models
567 Liberty Lane, PO Box 434
West Kingston, RI 02892
(401) 789-1955
http://www.riwire.com/