I really need to just start a new thread for the steaming turd, but today brings more fun:
As for the sending unit, it's actually accessible from the side, no need to drop the tank. However, the tank is pretty beat up, so I'll probably swap in the one from the parts car in the future.

I got the headlight switch out, it looked ok. So I disassembled the pot, and hit it with some contact cleaner and a brass brush. Put it back in and voila, dash lights. Then I rewired the HEI with 12awg; can hardly believe the shop used 18awg. Also, they tapped power from the fuse box by jamming a spade connector into a fuse. I improved it with a brass fuse tap. Then I used a cheapie crimp on tap connector on the new ignition wire, to feed the volts guage. Found an Orange wire hanging, and a quick investigation showed it to be dash lamp circuit, so I routed it to feed the guage cluster under the dash. Using the parts car as reference, was able to I.D. the proper wire for the wiper washer pump.

I'm almost ready to risk driving it to work tomorrow.