The low priced harnesses work good for me. Spread the harness out on a big table. Sort out the wires in groups to the location. Underhood, interior, & rear. Cut off the wires to units you are not going to use. Leave a short wire to tie on to if you latter add something on. Install the fuse box & string the wires. Cut off excess & splice the socket or connector to the wire. Solder each connection & use heat shrink tubing. Leave plenty of wire to the instrument panel so you can pull it out to service it.
If you try to build the harness yourself you will need 25-50 spools of assorted colors & size of wire. It will cost much more then a ready made harness.
George
