ORIGINAL: cum'n thru
I was under the impression that the regulator was needed when the tank was placed further aft ( at the CG ) that it was too far to push fuel with supplied pressure of exhaust. As far as the tank being too high wouldn't mounting the engine in the upright position correct this? Flooding is inherant in any plane when the engine is mounted inverted. Normally I will spin the prop several times after fueling before starting. It never kicks, spins a prop or runs backward.
As jrjohn mentioned, you are correct in that both situations can be cured by a regulator.
You won't need a regulator if you decide to mount the engine upright, but since the plane was designed for an inverted engine, you'll have a very odd looking plane. Somewhere in these 50 pages there are photos of someone mounting an engine upright, and although it worked, it looked very odd. If you don't mind the asthetic drawbacks go ahead and mount the engine upright.