I did some more looking into this and I guess I did not ask the question right.
Its a Slow Poke and I am changing from a .40 2 cycle to a Saito .50 and was wondering if the prop shaft has to be on the same plane as the old engine prop shaft. Same level up and down to say it simpler, just trying to make this clear as I can. I don't think its a big deal on that plane, as long as its close.
I think from what I read that the thrust line should be in line with the main wing center line, may be a little down thrust if needed.
sticks