If the stock wiring isn't hacked up too much, my *opinion* would be to keep it. GM did a perfect job designing it, all you end up doing is duplicating GM's design with newer parts essentially. My friend just went through his, removing all the excess miscellaneous wires previous owners had stuffed under the dash.
The '85 fuse panel has PLENTY of 30amp accessory terminals that can be utilized, I've got tons of stuff plugged into mine, even doubled up with factory locking connectors. I just added a small fuse holder like shown in the picture above to protect each circuit with the correct amp fuse. I've done quite a bit of wiring on mine, adding 4wd indicator light, TPI, electric fans, etc., so I think I've got a good handle on this wiring, or at least how well it was designed, especially for expansion.
For the wiring I had to add that I duplicated original GM, I used weatherpacks, initially all from here
Weatherpack stuff Later on, I just started taking my de-pinning tool to the wrecking yard and getting connectors from there. Just buy a bunch of the male/female pins, the seals for them, and you won't have to worry about mixing wire colors up, etc. when splicing. The smaller flat connectors GM used later on might be ok, but most I've seen (except the relay connectors) aren't made for much load. Weatherpacks seem to be large enough to handle just about anything, short of the battery cable itself.
I didn't buy the crimp tool, I used wire crimpers or needle nose pliers with good effect, then soldered the wire to the connector. Haven't had a single problem yet. The depinner is necessary IMO. Ballpoint pen refill is supposed to work as well, but I had no luck with them though.
Fuses arnt that expensive, theyre easy to replace, and if you do a good job with youre wiring, youll never blow a fuse anyway.
