Mr Cox

I think an upright engine would destroy the lines of the plane and I didn't want to cut through the nice looking cowl.
The position of the tank is very important with inverted engines, make sure that you can get that low enough, it needs to be at the very bottom of the fuselage. Battery goes on top of the tank right behind the firewall. I have changed that since the very first image in this thread was taken.

I would have liked to play a little with the wing incidence on mine, I think that it is set a little too high, but that is hard to do with the current wing attachment. Instead I've increased the engine downthrust (at the engine mounting lugs), it is not the same of course but it reduces the climb at full throttle a bit.