Its been about 10 years, but IIRC I was rich at idle, fuel pressure was stuck in the 45-48 regardless of the regulator adjustment. I did not have it tagged yet to drive it on the road. I cut the fuel line just in front of the passenger side rear wheel well, just before it snakes up behind the rear seat area. I blew air from the line at the rail to the cut I made and no restriction. I then tried to blow air from the cut to the tank and bingo....it was somewhere where the line snakes up to the tank. I just rain the rubber hose from the cut location to the sender until I got my S/S lines.
If you don't want to cut the line, just find a fitting that you can screw into the return port on the rail, then run a hose into a fuel jug or with a longer rubber hose back to the tank filler neck. You only need to run the car long enough to see if it corrects the problem.