I like to overpower things as much as the next guy and i felt that Kyosho's specs as far as engine sizes was a little undersized but, come on, twice the recomended sizes, how fast is yours going with a piped .91?, i would think that a normal .60 two stroke or maybe even a ys.61 if you wanted a rocket. probably the best all around overpowered engine for this ship would be a ys .63 and it will be faster than the Saito .72 and real close to the Saito 100.
I have a spare Chevy 350 if you need a little more vertical!! it would probably just about fit in that big Gee Bee cowl too.

Gee Bee Jim, what did you use on yours and what is the vertical like?, how much nose weight did you have to add?