73' B3 340 Duster pro touring build

Ross,
12 volt DC wiring is very basic. I know every body wants to hide every bit of the wiring system. That's good if its very basic. The minute you leave basic the most important skill is record keeping. In order to keep records EVERYTHING needs to be labeled and a "standard" needs to be established for the system.
SO... choose a connector style you are comfortable with, I happen to like Molex, but there are others that are just as good. My standard is if there is a ground in the connector population of wires it is always at the pointy side of the connector.
Get some clear 3/16" heat shrink and a Brother Ptouch with 1/4" labels and label every wire in and out of he connector. Then put together an excell spread sheet or portion there of for every major connector say 4 pins and up. give every connector a number and record it all.
I cannot tell you how many times those records have saved me and allowed me to find system problems as I went. I am sure they will come in handy yet again.
Andrew