I don't think there is need for a spacer because the cam lobe will just rotate without interference, They make blank covers to cover the hole. Just make sure you have a good gasket on there.
The downside to electric fuel pumps is most of them are inside the fuel tank, they always go out when the tank is full (Joke).
But seriously, with an electric fuel pump, keep the tank at least half-full because the fuel keeps the electric pump cool.
Most of the fuel pumped by electric pumps is just recirculated, this keeps the pump cool and helps prevent the gas from Gelling or waxing up.
