[GaryL]

This is on my theory alone, but you should be able to pull the fuse for the fuel pump, install a mechanical fuel pump and fuel pump rod in the block and that fuel pump should be able to pull the fuel through the electric pump. I added an electric pump to one of my old Firebirds and only used the electric for racing and never had an issue, but never tried it on a factory setup.

 

[GaryL]

On most carbs, the needle and seat will only stay closed up to about 7 psi, after that it will open and overfill the bowls.