Sounds like you have two separate problems, maybe related.
If your plugs are getting fouled you have too much fuel not too little. Adjust the idle mixture as suggested, I would use a vacuum gauge for that. Also check the float level, it may be flooding enough to foul the plugs but not enough to cause running problems.
Seems to me the regulator would be the problem with the low fuel pressure reading. Reducing the pressure by by-passing to the return line but having enough at the carb to run the engine.

Curious as to why you have an electric pump in lieu of the mechanical? The mechanical pump on mine feeds the 464 cubic inches through an 850 carb up to 7,000 rpm with no problem.