Bad experience
Hey,
This post just reminded me of a bad experience I had many years ago with my 74 four speed. I had a few problems like you described here, but did not pay a whole lot of attention because I could push start the car very easily. One morning about 5:00 a.m. I was cruising around 70 mph down a narrow road. I hit a few bumps and everything went out, no lights, no engine nothing. I thought I was going to die because there were no street lights and the moon was not bright. Suddenly I hit a few bumps and the power came back, the lights had dropped back in the hole so I had to wait for them to raise. When they popped up I was on the wrong side of the road heading for the ditch.
Found out later that day that the positive terminal to the starter was loose, and or the upper stud on the solenoid was cracked loose. It was causing the engine to loose all power, and thus not only did the engine stall, but lights and all went out.
You might jump under there right away to avoid the same thing happening to you.