Worked on it some more tonight...beefing up the fire wall and side walls (engine box) to handle this heavy but powerful engine.
As I mounted the Moki on the airframe for fit I realized the engine is really just right for this plane...the engine size is a close match to scale. The only issue is the weight of the engine. But maybe that can be to my advantage when it's time to balance. As a last resort if come into balancing problems, I can unbolt the engine box and slide forward or backward as needed and drill new holes and refasten.
Does anyone know if Duane Habets is still making and selling these kits?