I have the same engine in the same plane, although mine is less than ten pounds. It flies it very well, 15x8 APC as I recall. Your problems are apt to begin when you try to run it with a Pitts style muffler. You may have to plug one of the two muffler exhaust pipes, or put an OS 7D carb on it, as I did. I have a newer Series 3 ASP 108 and it has an improved carb, so if you could get that carb (or the Magnum carb, same basic engine) you would have a nice running engine.

Clair