So why won't you use a mechanical fuel pump?
500 hp six pak engines work fine on a mechanical pump.
The main reason is to deal with current gas which boils and vapor locks more easily. As most cars use pressurized EFI, vapor pressure of gasoline is not controlled to the lower levels of the 60's and 70's.
My '47 Power Wagon, for example, would not re-start after hot soak at all unless the fuel pump and adjacent lines in the engine compartment were hosed down with cool water. It would also cut out rolling on a 90 degree plus day.
My '78 Ford F250 had borderline vapor lock running and was very hard to start after hot soak. When I added a deeper tank + longer pickup, it also would cut out running at higher load in hot weather. Check showed fuel pressure dropping to near zero at the carb.
An electric pump fixed both... as a bonus, the carb bowl fills faster after sitting and much less cranking on cold start. The trucks are functional and fun again. As much as I would like to keep it simple, the electric pump can help keep these vehicles rolling.
