Hi Russ -
I can't really help, but I recently assisted a family with a 1925 with the same fuel system. The hobbyist restorer had installed a 6 volt fuel pump (and a 2 pound regulator) and vented the gas tank cap. After discussing this with him, he had tried to get the pressurized system to work, but was never successful. The pump housing was still on the car, but he had never been able to get everything to work in harmony.
I am sure some of the owners of cars with these systems will chime in, but just wanted you to know that there are some not-so- elegant workarounds.
Someone no doubt is rebuilding these systems, it is just a matter of finding the person or parts.