This is what i did to my fathernlaws 47 p15.
Before I took the wiring harness out of the car I labeled each wire eactly where it goes.
Then I unhooked eveything, pulled the entire harness out of the car.
Then I laid it out on the shop floor and started rebuilding the wire harness one wire at a time retagging each wire as I tagged the original . When your done you should have two wiring harnesses, identical in length and shape. Both tagged and the new one ready to reinstall.
As far as wire color either you can draw out a color diagram yourself, or use one color of wire because you tagged both ends of the wire.
By the way if you take clear box tape and encase your tags they will be readable for years to come. They will be water proof and grease proof. Also the ink can't run.
Also its a good idea to put the old one with the tags still in place in a bag or box in storage, so you can have a reference for latter if you ever need it.
I used one color because of expense.
His harness has been in the car and worked flawlessly since 1992
ps. Make shure you flux all your wires before soldering. A cold solder can be difference between failure and success.
OH, by the way pay attention to the guage of wire you use, you can make it out heavier guage, but don't go to lighter guage. The wire can over heat.
Hope this helps Dale