If the cam is hot enough that idle vacuum is low (despite best ignition setting) an easy partial fix is a vacuum storage tank, simply an empty air-tight can connected between the manifold and booster with a check valve. No sizes, no adjustments, just hook it up. The can re-charges to highest vacuum available whenever the engine supplies it (cruising, trailing throttle). It allows several power-assisted low effort stops (instead of just one) in traffic. I used the Chrysler slant 6 can many times, the Summit/Jeg's is $$. I've seen them made from all sorts of containers (2 quart tomato juice) that will hold vacuum and can have 2 fittings securely attached. The bigger the better but mount it close to the manifold using the same hose size as the booster.
