Any of those vacuum pumps either aftermarket or salvage should EASILY put 20-22 inches on the booster depending on what the Hobbs limit switch is calibrated to.

I read lots of these vacuum pump threads where somebody leaves the booster connected to the engine and T's in the pump and can't understand why the booster still won't perform.

If you're OK with the way the car performs other than the power brakes, shop around for a vacuum pump with a built in limit switch that cycles it between say 17 and 22 inches +/- , hook it directly to the booster after eliminating the hose to the engine, and you will have go and whoa.

No way you can change a cam for less money and aggravation than a vacuum pump even at SSBC inflated prices.

Kevin