Jack,
Easy things first.
The ignition switch is overloaded. The original Lucas unit wasn't designed for street driving. If you are willing to make the hole in your dash a bit larger, I'll send you our
NEW IMPROVED! switch.
Cooling:
I think that you may still have a bit of air in your system. The best way to bleed it out is to tilt the front end up as much as possible and bleed from the top of the engine.
If that doesn't work, there are a couple of electric water pumps that can be wired to the fan circuit in series with the mechanical water pump, or used to substitute for a gutted pump.