[Tom Goldman]

Chuck's got it right.
Leave the trick stuff to the COMP racers.
I've run a vacuum pump for over 16 years and never had any problems pulling 15-16 " vacuum when all the other leak points are sealed up.
Fuel pump block off plates, distributer gaskets , manifold corners are prime leak culprits.
If your engine previously had minor oil leaks,don't expect to pull much vacuum .
HP gains are relative to ring packages ,end gaps and bore condition .