Flow Control valve needed
What is needed to connect a GM p/s pump, rated at 3gpm, to a Mustang II rack, using 2 gpm, is a flow control valve. Speedway Motors has them, under $20, when I bought mine. It screws into the back of the p/s pump, replacing the control valve already in use. I have a the same set up and it cured my problem. Problem known as the "twitch" commonly caused by mating a GM pump to a Ford rack.