Seems like a lot of people use an Airtex E8902 6V pump. I found one guy that posted he installed one and the instructions said to use a 10 amp fuse.
I wire mine so the early Ford ignition switch controls a relay that powers a separate fuse block. The relay handles the amperage instead of the factory ignition switch which is probably not rated to handle the ignition and the fuel pump. The relay controlled fuses provide the voltage to the ignition, fuel pump, voltage regulator... the electrical parts that make the engine work. When I turn the factory switch off it stops the ignition and the pump. That way I can't turn off the ignition and forget to turn off the fuel pump. I also run the pump wiring through an oil pressure cutoff switch that is bypassed while cranking. You can still put an additional toggle switch in the circuit or a momentary switch. I add extra bare spade connectors to switch's and relays... and I carry a spare jumper wire so that if a relay, oil pressure cutoff switch fails I can quickly bypass them with the jumper wire.