You can try moving the ADV/dosage unit to the top of the shell, swapping it with the OPV. Drill a hole in the center of the lid so you can push down on the diaphragm with your finger.
Martin at tecme has the right parts to help you. Another alternative is to buy his new ADV that fits straight to the P-port, but you still need to move the OPV.
Check here for some ideas.
/GKAM