One thing I did not mention above, is that the pressure is measured at the inlet of the carb per service manual and at 500 rpm. Pressure at an outlet of the pump should be higher. It then drops as it climbs the engine, goes through the various twist and turns, and separator. So that pressure rating in SVM is after separator on HP engine. So if a AVS or AFB can handle 8psi on a 426 or 440 at 500 rpm, it can handle it on a smaller engine. You just do not need the volume.

Too little pressure at inlet and you probably do not have volumetric flow for WOT.