Doug, I am sure that you will find the performance of the Roo awful with any prop
setup. I think that is better to wait a little more and save to buy a turbine. There is a good turbine of the 12 lbs range that is sold very cheap, the FT-500 (a.k.a. ram500) from Frank tiano, for about 1995 dollars. The kangaroo will fly nicely with it. Of course it would be better if you spend 1K more and buy a P70 or a p80.

Rgds, Enrique