New clutch setup won't disengage

I don't think that's right. A larger bore master will take MORE pedal effort, because it has more square inches of piston. The pounds per square inch also increases, as the clutch springs deflect more. So, (pounds/sq in) * (sq in) = (pounds at pedal). PSI larger, piston larger = pounds at pedal larger. You may be looking at this from the slave end, not the pedal end.

I can't add any more pedal stroke because it's already on the floor at 3/4" slave travel. The overall leverage is fixed in the clutch, fork, slave piston, master piston, and pedal ratio. The only way to move more fluid to the slave is a bigger master piston. Or move the same fluid but decrease the reduction ratio at the fork (hole closer to pivot) so the fork will move further with the same 3/4" slave travel. Both will increase pedal effort, doing more work.

Think about brakes, same principle... the reason to go to a smaller master is to decrease pedal effort at the cost of increased pedal stroke. Bigger master, more pedal effort, shorter stroke.