Electrical issues - Mainly alternator based

[chappys4life]

A few months ago I picked up 70 gmc c1500. Unfortunately it has had a lot more gremlins then I was hoping but working to slowly fix them. One of the biggest issues is wiring. I looks like a drunken monkey has attempted to update the truck when they added headlight relays, si alternator, classic auto air, and a radio. The ac main feed wire was jumped off the cigarette lighter and used a wire nut. I think a electrical fire or overload happened as behind the cluster there where a lot of melted wires that where brittle or exposed wire sections. I cut the wires back to fresh copper then soldered in new replacements with a new ignition switch. The speaker wires where twisted to the stereo then taped with no connector. Now I am trying to fix the alternator wiring and go to a 12si as it sounds like the 10si bearings are going.

I have a 12si 95 amp alternator and my plan was to run a new 6 gauge wire to the battery with a inline 125 fuse and ditch the starter connection as nothing else is connected. When I was looking at the alternator I saw a wire going to the starter and another connected to the bulkhead plug on the firewall driver side. Thanks to mad electrical I am learning a lot how chevy did it (I have worked on more fords so a slight learning curve but not bad). From what I can tell the wiring from the original generator to voltage regulator burned up (see pic below) and someone did a conversion and but only 1 wire is in the 2 plug connector (see pic).

So now I am rethinking life and want to make sure it sounds like a sound idea until I order a new wiring harness. I am in the middle of building a 55 chevy that is killing my garage space so this is a slight cleanup and get by until I can pull it in the garage and take my time.

The plan is:
- take red wire from alt that attaches to bulkhead for main power into the fuse panel add a 16 gauge fusible link and connect it to a junction terminal on the firewall (also replacing most of the wire as it looks melted and no fusible link currently)
- run 6 gauge wire from alt to battery with 125 inline mega fuse
- alt connector #1 terminal 6a 50v rectfier diode #2 terminal jump to batt post to by pass any other junk wiring.
- add constant power relay 85amp to hook to the battery for big power items like aftermarket ac, autometer gauges, then trigger with switched ignition probably from fuse panel for now

I already replaced the fuel line and filter just a pic before I got to it.
Also what is the terminal block in the last pic used for?