Glenn,
Is this an R/C engine with a carburetor or has someone added a venturi and needle valve?
For a set up to start I would get a 270 diameter venturi with an aeroproducts needle valve assembly, add 1 extra head gasket (.008 thick shim), use a hot glow plug like an Enya #3 or a Thunderbolt R/C long, and start with a 12 X 4 APC prop. Should be happy in the 9,300 to 9,500 RPM range.
From there it will depend on how it reacts.
Randy Cuberly