Just a suggestion. You might want to mount the engine inverted in a test stand where your tank height is the same as your bird. See how this works before putting on the plane itself. This could be especially valuable if you have to break in a new engine anyhow - why not do it all on the test stand instead of on the plane where things can get more complicated. You'll certainly see what gyrations you have to go through to start it inverted...

Good luck!