All my electrical woes.

I've got the wiring diagrams here in my lap. I may not be able to help though, here's why I say that. I can see the red with white tracer that should power your radio in my diagram and in the picture of your fuse box. Since you already stated you're not conserned with what you already know is wrong,
""The radio is low priority right now as it does work. That's one I can work on over time.""
how can I possibly help you ?

I will tell you something you wont find in the service manual.. The gauge voltage limiter or nothing else about the instrument panel will function properly while the panel dangles from the harness connectors.
The pot metal housing requires chassis ground that is achieved though the panels mounting hardware. If you want to do switch on diagnosis while the panel is out you will need to supply a ground jumper. (These sort of things aren't in the manual because a qualified service tech should know the basics. )
I highly recommend adding a dedicated and perminate ground wire.

Going back to the pic of your fuse box, the tach wire is in the wrong place. That added on spade with the large red w/ white tracer is battery feed for headlights and such , hot at all times.
The add on spade beside the large black wire is your accesory port for the tach. The large black wire is hot in run and comes from your ignition switch. It feeds power to the heater fuse and the radio fuse. It look like its been over heated too. If it hasn't failed at this fuse box end it may have failed at the ignition switch connector.
Hope something here helps