With a larger main tank and the 2 saddle tanks, I think you can get close to 80 callons of fuel on board. Hmmm, images of the Hindenburg come to mind... /forums/images/graemlins/shocked.gif
Since you're planning to go EFI at some point, keep in mind that you'll need a selector valve that also controls the fuel return lines. When you're taking gas out of tank 1, you also need to be returning the extra fuel back to tank 1, etc. If you plan to use in-tank fuel pumps, you'll need one for each tank. An external pump, after the selector valve might work, but the engine may stumble a bit when switching tanks, due to some air in the line as the valve opens the line to the next tank being selected.