There's a lot to an EFI fuel system. It all breaks down to fuel pumps, filters, and regulators.
Fuel pumps: In-tank, inline, or for a perfect retro project, a replaceable fuel tank with the pump built in.
Fuel filters: Select filters that are not restrictive at the flow volume you need. You need 10 microns or better before feeding any fuel injection system.
Fuel regulators: Again, choose a large enough regulator with lines that do not restrict fuel flow. Add an analog gauge to make simple, quick checking of the pressure.
Fuel type: Not all filters will handle the more exotic fuels such as Methanol. Check it!