The bulk head connectors are always a possible problem area. A lot of it depends on where the car spent most of its days, damp cold storage often causes issues with the bulk head connector.

I bought a 75 Daytona Charger that spent a good share of its life in a wet garage. I had a hit or miss electrical issue. After chasing it for several months, I discovered that somewhere along the way, the bulk head connector was separated and cleaned, but when it was reassembled, they didn't get all the spades pushed completely in. The car would run great until it would die on the road. About the time you started checking things out, it would fire up, and could run for a month or more before it died on the road again. One day, out of frustration, I took a screw driver and pushed in all the wires in on the bulk head connector, about 1/2 of them pushed in at least an 1/8" . Never had a problem with it after that.
Check the bulk head connector! Gene