Guys - I agree with all on the stellar job you're doing on your build.
I've covered this elsewhere but was unable to find it in the search so here goes again;
Diaphragm or Gearotor positive displacement pumps are best used in a lifting situation.
I'm planning on using a pair of these pumps by Purolator-Facet. They are made to lift fuel up to 10 feet and don't require either check valves or priming. They're not cheap but they're not going to leave me sitting there wondering how to get my car started.
The best (cheapest) place I've found them is Aircraft Spruce;
05-0082940223 PUROLATOR DURA-LIFT$140.950 Pilot Supplies, Avionics, and Homebuilt Aircraft Parts from Aircraft Spruce and Specialty Co.
They are also sold under the Thermo King brand name for use in Truck Reefer units that have to pull fuel from the truck's tanks all the way up to the Reefer engine.
More specs: Dura-lift pump Features:
- Self-priming with a 10 ft. (3m) lift capacity - Built in check valve to prevent back flow
- 4 hour dry run (how good is that!)
- 80 micron serviceable filter
- 30 GPH
- 9 to 11.5 psi
- SAE J1455 Certified
- Transient protection
- State of the art sealed electronics
- Reverse polarity protection
- Corrosion resistant: over 1000 hours salt spray
- Durable transparent fuel bowl
- Light weight - 3LBs (1.3kg)
- Height 7 1/4” "(180mm)
- Low power requirements - 1.4 amp average
- Self regulating (No regulator needed!)
Hope this is of some help... Please keep up the fine work!!!