To be honest, you have no need for the regulator. I have an 80 gallon compressor and with 140 line psi I can not put more than 70psi into the tank wide open without regulators. I have the relief valve set for 65psi and the relief valve opens up and 70 is all it will push to. Drop the regulator, install the gauge on the "T" where th relief valve is. Now on the other port, add in a reducer bushing, a 1/4" elbow, a 1/4" valve and the air line nipple. Simple to do and very cheap. If you set you your vacuum pump like mine, all you need to do down the road is to buy a combo gague to replace the one that comes with the tank and set up the vac-pump with an air chuck and nipple. I added in two 90-degree elbows to keep it tight and to blow the air away from me out of the vac-pump.
Very simple, litte weight and "hang over" and not too expensive all in all. There is no need to sepertae the PSI-inlet and the Vac-inlet in you buy a gauge desgined for what you are doing. Watch the gauge when you fill it and remove the hose when you are done and you have no use for a regulator, it's just one more thing to fail or leak.
Oh, and just to be fancy I had this fitting in my tool box that looks so nice inside the tank. It's just a compression fitting elbow, but the nut and sleeve looks so nice.
And this is the vacumm pump off the tank, just plug and play inline between the air hose and watch your gauge.
All the stuff can be bought at:
www.surpluscenter.com