Is the wiring harness butchered up?

Ideally, you diagnose a problem and determine what is wrong before you start throwing parts at something to repair your car.

That said, it Could be that the problem is mainly with your headlight switch itself. It might be the source of most or all of your problems.

The headlight switch doesn't just control your headlights, instead most all lighting control passes through the switch. On vintage cars, lots of current passes through that switch plus they are subject to corrosion issues over time.

Headlight switches aren't all that expensive or difficult to replace, but in the end, that may or may not be the problem. If it were mine, I would visually inspect the wiring and if nothing else was obvious, replace the headlight switch if it is Original or really old just on general principle, but that has to be your decision, not mine.