I started off w/ an Aerospace vacuum pump kit which is a total piece of crap. Had 2 pumps fail and the mandrel is junk too. Never pulled more than about 6-7" w/ the regulator closed.
The regulator is mounted on the intake side of the pump itself.

I switched to a Moroso 4 vane pump and CV products mandrel drive setup and couldn't be happier. It pulls 10" at half throttle where it is set right now...honestly not sure what it pulls at WOT.

Mine pulls from the driver's side valve cover w/ no baffle at all. No issue pulling too much oil. I drain it after I get home from the track.