making wiring harness from scratch

Guys thaks for the feedback,
I was incorrect in the original assessment of the wire gauges. They are 18 &14ga I will be getting some 10ga for certain runs.
Because this is elevator traveler cable there are about ten different colors combined in the two spools.
The reason I went chasing this stuff is that every piece of wire is individually numbered along its entire length. So Im not at all concerned about matching color codes to the existing harness.
When this is done I will have a spread sheet with all the numbering and terminations, and a complete CAD schematic for the car. I already have some of the engine compartment's added wiring done as far as the safety, security and oiling interlock system.
This is also the time I have to decide where all the stuff in the trunk will be located for wiring purposes. As one person wrote this is where i have more time than money so no rush here.
Andrew