Hi David,
Having been through a similar situation, where after having some welding done, the loom was fried, I bought an autosparks loom with Alternator conversion.
I did consider making my own loom, but purchasing all the different coloured wires of the correct current rating meant the cost escalated enormously.
I have attached a colour pdf of the wiring in my car at that time. (various mods and changes since). This file is quite large so if you have a problem with it, I can send it direct.