RE: engine recomendations...
If you want a 2-stroke, consider the Magnum XL-28 or XL-25. Both are around $60 from Tower, about $25 less than the OS 25 FX.
Chuck, just to be contrarian, I still think your Corsair would be nicer with a suitable 4 stroke and dummy cylinders to make up the rest of the radial.
-Scott