What is my electric fuel pump? I spin off the star nut on top of the air filter and trickle in half an ounce of gas and tighten down the nut and close the hood! This usually starts the car and I might add my 50 Mercury Sport Sedan is still on 6 volts! Those flathead V8 fuel pumps have a very short stroke, low volume and pressure and will not fill a dry carburetor by cranking on the starter. I'm going on 40 years of ownership still running a flathead with 6 volts and everytime spring comes around the wing nut gets spun loose and a gulp of gas is dumped down. Yes if slightly too much the accelerator needs to be held down but also keeps the engine running longer as well and long enough to keep it running.
That was a VERY GOOD POINT brought up about in the event of an accident the fuel pump will keep pumping adding fuel to a possible fire or make things more hazardous!!
Now the check valves that Barry pointed out and yes they can cause problems!! My fuel pump is sitting on top of the intake manifold way above the fuel tank. Your 383 and 430 Mercury engines from the late 50's had them higher up as well. As Barry mentioned the check valves are on the inlet and outlet and not only do these valves get worn but the seals that seal them in the housing also shrink and can cause bypass. Of course your fuel can siphon back down to the level of your fuel in your tank creating a bit of an air lock. Yes the fuel pump can and will overcome this but it also slows down the filling process of your carburetor as well. Not only do they cause this but can also reduce the efficiency of your fuel pump.
Some people put a continously running electric fuel pump in series with the mechanical pump but be aware of the fact that if your fuel pump diaphragms leak or rupture, the electric fuel pump will fill your crankcase with gasoline. Some of the equipment I have worked on had the fuel above the transfer pump and if the transfer pump developed a leak you would find the crankcase filled with Diesel fuel.

Here is another solution instead of a questionable electric fuel pump, and that would be to start your car every month and let it run for a while to circulate oil around the engine and of course circulate fuel through the carburetor preventing the carburetor from becoming varnished!! When the fuel in the carburetor evaporates the float settles to the bottom of the float bowl. Also when fuel evaporates it creates varnish and where is your float again?? At the bottom with your float valve fully open and stuck from varnish. The total BS about Holley 4000 series being fire hazards is just that, total BS because ANY carburetor can have the float valve stick open and any carburetor can have the float spring a leak and fill up also causing the float to sink and cause the flooding!