The fuel system consists of two fuel pumps, a low pressure high flow pump (Holley) to get the fuel from the tank to a swirl pot, a high pressure (EFI) injection pump that takes fuel from the swirl pot and feeds the injectors.
The reason for setting the fuel system up this way was that I wanted to use the original fuel tank that did not allow for an in tank pump. So the low pressure pump pumps the fuel up to a Swirl Pot. This is essentially just a small pot that will hold approx 1/2 Litre of fuel. The Injection pump is then fed from this. This means that the Injection pump always has a readily available source of fuel.
If the injection pump was not fed from the swirl pot it would have to draw the fuel up from the tank. It would probably cope but I wanted to be on the safe side.
The actual diagram for the fuel system is below: