Only time I've had good success with vacuum brakes has been in my current NA el Camino. They work good. I installed a hydroboost setup in a pro touring style Camaro...bad ass. Neck snapping stopping.
I've installed vacuum brakes on a couple other NA cars, worked great.
I converted another 87 GN to vacuum, brakes were more dependable than the PM but sucked in comparison to hydroboost. Two of my buddies with GN's as we speak, have the worst brakes ever. Both going to hydroboost. I have hydroboost in my GN and look forward to good stopping power. There is a reason most if not all heavy duty trucks come with hydroboost. The shit works. If your pump can't handle running the brakes, it is probably on the way out anyways.
Sorry Earl, I can't agree on this one
I've done way too many brake setups and have found what works best for me. To each their own.
OP, whatever you do, be sure to change the proportioning valve if it's cast iron.