Bob,
When we switched-out the stock-tank for the cell, we started having a pick-up problem. If the high-pressure pump sucked air, the car would either die or fall-on-its-face. We couldn't figure-out how to put in a sump tank into my cell. So, we got a low-pressure high-volume self-priming pump and just put it in-line between the cell & high-pressure pump. Its only there to feed that pump. Some of the long vans use a booster-pump in the same way. That is were we got the idea. As far as the pumps, the high-pressure is a universal EFI pump (Master brand part #E2000, from Autozone). The other pump is one we bought at the track. I don't know the brand or model of it, but it was for a carb (something like 8-10psi). Both pumps are wired together on one switch (easy-on, easy-off). I hope this helps.
Where are you getting your parts? I've been having trouble finding things.