The holly regulator might work with the carter pump as it is a low pressure pump to start with. The one I used was a holly pump that builds 15 psi so I was forced to go with the return style regulator. The one that came in the box was just like the 12-804.
My pump is a holly blue and man o man does it pump fuel. The regulator that came in the box slowly creped up on the pressure thats why I went with the return style. It is 4.5 - 9 psi I must run 6 psi.