Time to remove and repair, possibly replace, under dash harness

hotrod swinger said
I am going to pull the harness, hopefully repair it, if necessary replace it.

I think this will be pretty straightforward, any tips?

With a more major repair - which yours is, laying it out on a plywood board may be a big help.
Some examples here: WIRING NIGHTMARE

hotrod swinger said
I enjoy soldering and I like a challenge, so I think I will remove it and examine it and make a decision.

Good plan

hotrod swinger said
Most of the connectors are in good shape, none of them are melted, including the bulkhead. Maybe I’ll just have to solder in a couple new sections and repair some areas with shrink tube.

Mmmm,
With that melting you may find it better and easier to replace the entire section of wire from juntion to junction.
Crimping the open barrel connectors on the bench is not difficult.
For splices you can order the open barrel splice connectors and use with or without solder. I don't usually solder them for use inside expecially If the wire needs flexibility in that location.
For heat shrink tubing, get several sizes in types that flexible and types that are fuel resistant (for engine compartment).

There are several good threads on crimpers, connectors and terminals. I think you've seen them or links to them.
The only terminals that can not be easily replicated are the ones that had molded rubber insulators and seals.