I think I found a good way to clean the terminals in the bulkhead connector. Don't know if it will be OK long term, or on heavily corroded terminals.
I unplugged the connector, and removed from the firewall. Then put white vinegar in a freezer bag, submerged the connector in the vinegar and put a rubber band around the bag/wires, and let it soak for awhile. Dumped the vinegar and replaced it with water, then rinsed with a baking soda solution in the bag to neutralize the acids. Dried with air pressure, and hair drier. Then coated the connectors with dielectric grease prior to plugging back together.

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 225 nitrous
64 Valiant Signet
64 Valiant 4dr 170

You didn't mention you did it, which you might have, but I would have included at least one post baking soda wash with at least one pure water wash, and I think the dicelectric grease is probably the most underrated preventive solution for this connection.

Didn't mention it, but yes, I did a pure water wash after the backing soda bath

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 225 nitrous
64 Valiant Signet
64 Valiant 4dr 170