Some will say you can use an adjustable regulator with a return but in my book if the regulator ever fails, sending EFI pressure to the carb...well that will be no fun. Blow the needle off the seat, spray gas out of the fuel bowl vent tubes like old faithful. My old roommate did a similar project and he just used a holley red pump, no regulator required.
There's plenty better pumps, I'm just saying something of the like.
Either that, or slap a mechanical pump on the timing cover and call it a day.