The AC/heater booster? Is that the black ball thing? Or are you talking about the vacuum line that has duct tape? You could cap the port or plug the line.
Are you reading vacuum when it's warmed up?
If the fuel pressure is too high, you can either find a fuel pump that puts out less pressure or easier to do is to put a regulator to lower the pressure to the carburetor. I usually use a tee that connects into the fuel line to check fuel pressure. Just be careful. You don't need to read it for long, and it will jump a little if you tee in because the needle will be opening at idle, but you should get a good number.