Heck I had headlights go out on the interstate. '75 valiant 4 door.
That was interesting...
At least the breaker was working.
I think every car needs to be evaluated on what conditions are found/observed.
All of the damage from that recharging stunt I pulled were in the bulkhead terminals. The alternator output terminal had melted off most most of its dust/moisture seal. That was the worst. Of course that alternator failed a year later - one of the stator winding wires broke right where they join. Was that in part from maxing it out for 20 minutes? Maybe.
Have I added a parallel altenrator line? Yes I have. It goes a terminal on the firewall and then to the ammeter.
I think Chris ought to do a post mortum on the fuel line and then examine the damaged wires.
Whether he ought to repair the factory wiring, or just buy a new engine harness, I don't know. really depends on how much time/money effort he wants ot put into learning to make nice crimps and rewrapping the harness.
If I was going to make changes, it might be to add a fusible link. I don't recall if the '64 has a ring terminal at the firewall or a Packard type push terminal. But we've seen both types damaged. I suspect the ring terminal while capable of more current is also exposed to more weathering and oxidation. Dunno.