Here's what I did. Modified valve with a feed tube tight to the body. The feed tube still comes off at the neck and a hopper can still be placed on. The pump base is mounted to the back body so that the gun still comes apart easy. Air is alot better with no blow back anymore.
Most of the time is in the pump handle and push rod. Stopping the blow back takes about 5 mins to do and can be switch back to semi in about 5 mins. I mostly use it as a pump, but have switched it back to semi to use like a pistol, just by removing the push rod and putting blow back on.