Help with brakes.

I agree with previous post. You can purchase inline residual pressure valves. I have them on my 54 chevy with a corvette MC and booster.
The application of the MC should not matter. I probably put 4 different MC's in a factory five racing cobra replica I built before I found one that had the proper feel without a booster, the reason being the car was originally power brakes but they suggested removing the power due to how light it was. In that case I was playing around with piston diameter, nothing more.