Not sure if you're interested, but I made an adjustable FPR for about $10 and 10 minutes of time. The Ford CFI (Fords throttle body injection) cars have an adjustable FPR, but its not referenced to engine vacuum. I drilled a hole in the top (not the fuel side so its safe) and JB Welded a barb fitting into the hole. I then drilled a hole in a stainless hose clamp and tightened it around the barb fitting. I have pics I can post later. It only took a few minutes, and works like a charm.