I swapped in an AC fuel pump that was most likely original to my Galaxie, but it would not build pressure. My next step was stealing a Carter M4008 from the Galaxie motor.
I had the exact same problem - it ran for about 30 seconds and then a fountain of gasoline burst from the secondary vent tube. Then the battery died when I went to crank the motor again and read pressure.
The Carter website lists this pump as 8.0 psi "Maximum Pressure." (Edit: I now have a reading - 6.0 PSI, which was fine with the Autolite 4100. I checked the rear float, all was good, checked the needle and seat, reassembled, and then the front vent tube splashed over again. The O rings I have on hand are nitrile, so I might need different ones. At this point, I think I might need to fully disassemble and swap needles, unless I can get o rings separately. )
My vintage HP Books Holley book arrived via USPS today, so hopefully I will figure something out. Thanks for all the help so far!