All my electrical woes.

One thing at a time please. So you did find the radios harness plug. Red is radio power. The orange is idial illumination. It gets power from the fuse box but only when the headlight switch ( park ) supplies power to that fused circuit.
The large red wire in the ignition switch connector is power into the switch from the fusible link. The black wire is that same power throught the switch in on position to the fusebox. That wire does have a welded splice where it branches to wiper switch,instrument panel including the limiter, etc..
Like I said before, you can power it up with a ground jumper on the instrument panel. Beware those 2 connections at the amp gauge ! Those are hot at all times.
Once we know the instrument panel and the fuse box is getting power then we can go after what works and what doesn't.
hop this helps