I have an electric fuel pump mounted back at the gas tank of my Fairline with a 312 stock engine. I suspect it is faulty or not producing enough fuel to the Holley 4 barrel. I have a clear gas filter (new) and the flow of fuel looks very insufficient. The car is hard to start and does poorly on acceleration. The air filter is new as well. Wondering whether I should go back to a mechanical pump or replace the electric with a proper replacement. The specs in the manual show that at 500 rpm, the pump should operate at 3.5 to 5.5 PSI and produce a volume of 1 pint every 30 seconds which I calculate to be 15 mph. How do I choose an effective fuel pump if I decide to replace the old with the new? Thanks for any help!

Check the pump pressure - you will need a pressure gauge.  Check flow  by allowing the pump to fill a container for one minute.  Ideally a container that is graduated is preferred  but any container with a known volume can be used for reasonably accurate measurement.  If flow or pressure is low, it still may not be the pump.  You must also be certain that there is no debris blocking the inlet side or loose fittings/clamps/corrosion allowing air in on the inlet side.  If that is happening, then no pump will do a good job.

One way to trouble shoot fuel supply as the hard starting problem is to use starting fluid.  If it always fires up easily with that, then it probably is a fuel supply issue.  When I say fuel supply, I mean everything up to and including the carburetor since the float, needle, jets, etc are all in line, supplying the engine with fuel.  After that, you can use a remote fuel supply (or be careful with a funnel and some hose) and gravity feed fuel to the carburetor.  That eliminates the entire fuel system before the carb.  If it is still hard starting, then the feed to the carb is not the issue - it's the carb or something else (timing, compression, etc.)

I think you more likely have tuning issues.  Just about any pump should provide enough fuel to fill a fuel bowl and start the car.  The tests above will tell you if that particular pump does.

As far as replacement pumps, just about any automotive pump should work for a stock engine.  If you go to a site like summitracing, most pumps state the amount of power they support.  Just make sure it is adequate for your engine. My preference is Carter electric pumps.  I've been using one on a daily driver for probably 7 years now.  I tried Holley.  They averaged about 1000 miles each, under the exact same conditions.  They're a waste of time and money on a daily driven street vehicle.