See this thread:
Scubapro Second Stage Lever Height
If you promise not to tell, I'll let you in on a secret procedure that will work at least 80% of the time with SP barrel poppet designs. The following assumes you have a good lever and orifice.
1. With the poppet removed, run the orifice in all the way.
2. Back the orifice out EXACTLY two turns.
3. Install the lever/poppet/spring/balance chamber assembly.
4. If applicable, install the adjustment knob and stop pin-back the knob out to the pin.
5. While holding down on the purge button, screw the orifice in (clockwise) EXACTLY 3/4 of a turn.
This should put the orifice so close to the correct position very little, if any, further adjustment will be required. It always works, except when it doesn't.
Try it and report back.