72 duster 360 NA to 390 Turbo

@rumblefish360
This regulator can be used with two different available springs, one low pressure like 3-20 psi for a carb and one high pressure 20-60 psi for efi.

Universal Return Style Regulator – Aeromotive, Inc
That's the one I’m using with the low pressure spring. The pressure at the holley efi pump is internally regulated, once I’m EFI which will require 58psi, once boost is applied there will be no upping of the pressure from the base 58. So I need to look at the aeromotive pump or buy another external pump.