I believe Mac's offers a 6V Inline Pump that does not require a regulator. I have one of these on my '32 that I have on a "momentary" switch that I use to prime the carb if the car has been sitting for a period of time. I can also use it "Full Time" in case of an emergency.
YES! I just bought one from FIFTH AVENUE ANTIQUE AUTO in Kansas. Their number is 785-632-3450.
Comes with a 30 micron filter. the really wonderful thing is they are gear driven. No more diaphragms being eaten up by the fuels we are forced to use these days.
They are 2 1/2# so no need for a regulator either. Runs very quiet too.
The Airtex E8011 on my '40 has 10+ years on it with no problems. I use it mainly for priming, but it has also worked well as a backup when the mechanical pump failed. They're available at/through most auto stores and on Amazon. I'm running a Holley 4bbl, so I don't need a regulator.
There is a high quality model with built in replaceable filter made by Airtex made right here in the USA. I recall it costing about $80 but do not buy some cheapy model. Ron Francis sells a neat aircraft toggle that the switch cannot accidently go on unles you flip the red cover open. My 40 convert has sat for about 6 weeks and I had to use it today momentarily to make the flaty pop over quickly. These mount neatly in the frame rails near the tank out of sight.
I just went through this. NAPA carter made pump # NFP 60504 12V pump works on 6V also at i assume reduced speed puts out 2.5 psi has filter attached and NO reg needed. Using on a 4 banger w/ 2 stroms 81. perfect. ken ct.