Guess quite a few of us have managed a PCP QB in one form or another.
In its simplest form:
All the smoothing/alignment/deburing mods outlined in the co2 tunes. New PCP tube shouldn't need to be smoothed/deburred.
Modding the valve a bit to make it a simpler non-piercing Delrin seal design (the issue valve stem doesn't live long at pressures higher than Co2 and the piercing pin assembly just clutters the air flow). If power is a goal, would search past posts on increasing the valve gas flow.
Increasing striker hit to the valve in ordere to operate at higher than co2 pressures.
HAd used the same PCP tube on a .177...then used it on a .22...ended up with this long barreled .25 that pretty well followed the above.