There is a difference between pressure and flow and i think you should measure both. without a pressure gauge you are guessing your at 5.5 lbs but you may be less still. And yes, the pump should provide enough fuel at all times.
I dont understand why the regulator in the system, not needed unless you are running a aftermarket high pressure/volume pump and even then most carb pumps are internally regulated at 6psi.
so ide get a gauge and hook up to fuel line and crank motor, then disconnect and put line into a bottle and crank. you should have answer to pressure and flow right there.
hope this helps