Re: Electric fuel pump on 1960's inline 6
I believe that the existing mechanical fuel pumps are considered much safer because they stop pumping when the motor physically stops running, regardless of the ignition key position. An electrical fuel pump may keep pumping fuel under conditions where you do not want it to pump, such as if the engine dies because of a fuel line break between the pump and the carbs or the ignition key is left on for a long time without the motor running. In short, it is probably not a good idea to reengineer the fuel delivery system from what was originally designed.
If the existing mechanicical fuel pump is not providing enough fuel to the carbs, you need to either rebuild the pump or determine if there is a restriction in the fuel line upstream of the pump.