What do I need for a proper under-dash rewire?

If you are good at wiring do what I did with my engine compartment. You can buy all the color wire you need on line in lengths, get a good Packard 56 terminal kit and good crimpers, a removal tool and go for it, not that hard. Just take it out lay the old one out and do one wire at a time. Reuse the connectors that you can with new terminals and also have a wiring diagram around easy to order the wire that way in the proper size and color. Think mine cost about 120 total to do with all the tools and parts. USE GOOD WIRE!