Poor brakes at low RPM

[John]

More specs:

duration at .006 283/300

Gross valve lift is .508/.511 but with 1.6 rockers that .542/.545

Comp cam claims I shouldn't have issues with vacuum but I told them at 10.5:1 compression. The seller told me that's the compression but I am trying to research the piston installed and head CC to confirm that. I have not run a compression test yet but I will be doing that next.