I just got off the phone with StreetsideAuto. and the fellow I talked to said that the Holly regulator was adjustable within the 1-4 psi range. In other words, I can dial in exactly 3 psi of pressure.

I don't see why that would not work.

Install the Carter in the back, and install the pressure reg in the LF underhood area. Dial in 3 psi of pressure and voila!

Plenty of flow with a limit of 3 psi of pressure.

Why would this not work?

Not trying to be snarky, but honestly why wouldn't this work?