You could use a Holley Blue regulator w/out a return. They are available in low or high pressure versions. You want the low-pressure versions. I do not know the part number off-hand but it's cheap. You'll need the fuel line from the reg to the carb and I suggest putting an inline filter between the two.
The in-tank pump I put in my Camaro pushes near 50 psi, I used the reg to cut that down to 8-10psi to feed the fuel side of my DP Nitrous. Works like a charm.
The reg is in the bottom right of the pic.