Rick, I am running the carb off of an Irvine Q72 on my .91. It has exactly the same venturi and neck diameter. I drilled and tapped mine for a Fox .74 header with a J-Tec snuffler in it. Basically they recommend one prop for it, a 14x6 which it will turn in excess of 11,000 Rpm. Mine is electric motor smooth and has never dead sticked. If you would like I could measure the venturi diameter of the original carb for you to see how the Perry compares. I run mine sometimes with a Davis Diesel head on it . In the Diesel configuration it turns a 14x7 three blade at 8,500 RPM. I suspect the Perry is the right one for it. If you would also like to have a Webra .61 Speed you can get one from Paul's in Fargo, ND. I love my Webra's. Davis has an excellent soundmaster muffler for this engine that would be much quieter and provide more muffler pressure than the box yours has on it. PS, Webras don,t need much nitro I run mine on Fox 5% with 18% half castor and half syn.