In that case, go ahead and put an OS 160 in it and call it a day. You're not going to get the performance you're looking for with a cheap gas engine. The weight penalty is ridiculous. An OS 160 on 5% should do what you're looking for and still perform well.

Even the lower end Evolution gassers don't crank the horses necessary. I mean it'll fly, but you won't be able to do a lot of extended vertical stuff. IMHO it will just be more trouble than it's worth.

I'm not saying it can't be done, I'm just saying you probably won't get what you're after with a heavy cheap gasser on that particular airframe.

-Mike