A few years back on my '86 had torn my hair out about gauges all failing ( you have 2 problems from the sounds of things).

I had mentioned my own gauge problem earlier with this thread.

Might also check to make sure your ground points are nice and clean. Emery paper is your friend.

Also check your fusible links; you've got way too much stuff messed up; that problem is upstream of all your systems.

On the headlights, you might want to take the switch apart and clean up the contacts and see if that's an improvement. They get corroded over time.