Check out [link=http://www.jettengineering.com/engines/bse40.html]JettEngineering.com[/link].
He has all this perfected.
Dub has a .76 in a .40 size case and it's lighter than any other commercially available engine in this size class.
Notice the RPM's he gets with the props listed and also notice how small the ports are, including the exhaust.