I don't have a wiring diagram in front of me at the moment, but the electrical problems are probably due to corrosion. Clean up all the fuses and slip-on terminals at the light switch and the hydraulic brake switch at the brake line junction block, for a start.

Engine won't start:
Could be water in the gas from condensation, or just that the gas has turned to something inedible. Remove SU float bowl covers, suck out whatever's in there, fill with fresh fuel, replace covers, try it. If it fires, you have bad fuel in the tank.

Make sure SU pistons are free to rise and fall. I've had them gum up from condensation and stick.

Or the timing is way off. Turn the motor so the timing mark of choice lines up with the indicator on the timing gear cover (i.e.: if you want to set basic timing at 10 BTDC, line up the 10 mark). Look under the oil filler cap. If both valves on #1 are fully closed (check rockers for free play), proceed. If not turn engine 360 degrees and check again, then proceed.

Remove distributor cap. There's a scribe mark on the body of the dist. that the rotor should point to. If not, turn dist. to make it so. Verify that this position is #1 plug wire on the cap. From there, working CCW around the cap, the other wires go to 3, 4 and 2 in that order.

Turn distributor slightly CCW until you're sure the points are closed. Turn on ignition. Slowly turn dist. CW until you see or hear a spark snap across the points as they begin to open. Turn of ignition, tighten distributor, put rotor and cap on. Try to start it.