I've used two of those Amazon wiring kits now with great success. Currently doing a bumper to bumper rewire on our first fire truck (1952 F***) with one and it's got such long wires I can almost reach the rear bumper with it. The front clip wiring is long enough you could easily move the fuse box anywhere you wanted if you had a panel truck, for example. There are circuits that become handy "extras" (assuming you aren't using power locks or windows, fan, etc) for any additions you might want to add later. They even come with headlight plugs and the standard blade type GM alternator plug (for the 3 wire style).
The current kit I'm working with actually has all the wires LABELLED which can save some walking back and forth (especially on a large vehicle). The whole thing was under $200 Canuck shipped!! About the same as taking the family to Boston Pizza for dinner.
Having also done a few from scratch, quite honestly I prefer these kits. Might move up to a more expensive kit for the next one only to compare.
