RE: Thinking of a Limit Q 500 and a .61 DF.
If this engine is a runner, those high pitched APC sport props can let loose, even below the recommended 190,000/diameter formula. I would not try this project with a cheap ARF. One little hidden flaw in the ARF Q500 and you will need a shovel to retrieve whatever is left. The big Rossi would have you hacking into the plane and moving things around to get the CG and to get everything else that got moved back happy again. The higher quality reenforced Q-500 wings that are set up for the 160mph class would be the way to go, then just build your own fuselage