I used a different control,Camsoft, but rebuilt a CHNC turret to do my bidding.
One key was the exhaust on the turret to control rotation speed. if set slow the thing would stall. If openned to run fast, it would overshoot the stop pawl. So, i added another air solenoid on the exhaust. With it open, full speed to the turret. Closed and very slow speed. Close this solenoid a second ahead of the stop pawl.
Now, I have extremely fast turret rotation that slows just before the stop pawl comes in.
P.S. I addded my index logic. Written in a different language, but logic is logic - works the same.