Bob,
On EBAY (ClassicCarWiring.com), I found these great laminated large color coded wiring diagrams that are precise, easy to read and useful when working on the wiring. When I got my brand new reproduction stock harness for my 59 it matches the colors on the laminated diagram. Measures 11x17. I bought one for my truck, my old Pontiac and my old MGB. They are inexpensive and work great for me.
The stock harness in my 59 is fairly simple and I could see how a handy, patient, organized person could put one together with the right color and sized wires, but I would be hospitalized if I tried......
Ralph