Buy an OS.46FX, if you live here in the USA.

Forget the bushing engines. They have a niche market, but they also require a fuel with more oil than ball bearing engines and at least some castor oil in the lube mix in order to last a "normal" life time.

You don't want an engine that is limited to burning 5% nitro fuel. Most clubs buy fuel in bulk and most bulk purchased fuel is not 5% nitro fuel. Too much nitro in an engine that is not designed to handle it can cause overheating, unexpected flame-outs and, eventually, excessive wear.

Good luck.