There are lots of ways to put a hydroboost system together with used or reman parts (some Chevy Astrovans had it). It takes some engineering and adjustment... probably more than my personal appetite with brakes.

Hydratech offers an engineered new system for older MOPARs which looks nice... just spendy.

Just for reference, how low is your idle vacuum?

http://www.hydratechbraking.com/