12 Volt vacuum pump problem

If you have 14@idle, IMO,you don't really need the pump.
All boosters I have tried (from 73 to 76 A bodies, and 77 to 80 FMJs),except for the older pesky dual-diaphragm;worked fine, down to 12 inches.Actually they worked down to a 9 inch idle in a stick-car, at all times except at first start-up. At that time I had to blip the throttle a couple of times to build some vacuum, before backing out of my stall. As soon as the car was moving out, the booster was charged and ready.