As far as engine choices go, you might want to try a Jett 90. Its' the same size as a OS 61 and turns an 11x7 prop 2000-16000 RPM. All engines are hand made in the USA to the customers specifications. They even make counter rotating crankshafts (engine runs backwards). This allows you to use any regular prop in the pusher configuration (more choices). Only reason I say this is because I'm designing a kit version of this very aircraft and, performance wise, the Jett 90L is an excellent choice.

I also have a thread documenting the progress while it's in the CAD stages: [link=http://www.rcuniverse.com/forum/m_4588489/mpage_1/key_/tm.htm]CLICK HERE[/link]

More info about the Jett brand of engines can be found [link=http://www.jettengineering.com/]HERE[/link]

My $0.02,

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