My Power Disk Brakes are frustrating me...

10"/hg of vacuum is way to low to operate the booster properly, I think 14 is the lowest and you can still get a hard pedal after 3 or so pumps

factory engines run 16+ "/Hg, you have a few options, add a vacuum pump to allow your brakes to work properly, change the cam; or remove the power booster and put a manual master cylinder on it