I think part of your problem is the harness not being color coded and the ID numbers falling off. What brand is it so others can avoid this problem?
I bought a harness from Hotrod wires. This harness is color coded using the same code as late model GM wiring. This is a universal harness and is not a direct replacement for a truck harness but I had little problem putting it in my '56. What questions I did have were quickly answered by the mfgr.