John; Your doing exactly what I plan on doing once I get this plane, soon I hope, have to convince the wife that it is a needed addition; the 511 Robarts with the Robo Struts is on my list; I plan on using a RCV 91CD 4 Stroke; there is an APC 11x8 4 blade prop I might try, not sure if it will work; I have run this engine using a 12x8 3 Blade prop with good results on another plane; the engine calls for a 13x6 2 blade, so the 12x8 3 blade worked and using the same formula of dropping an inch of diameter with each extra blade the 11x8 should work; just have to try it out, it would have a great scale look if it does work; the pattern guys use 4 blade props, must have some sort of advantage; I plan on installing the elevator and rudder servos on the inside, also plan on scraping the tail wheel and install a Kleet Plastics tail wheel, a little more scale looking, I may use a pull-pull set up to steer it. Doug.