Ok, here I am again, after much more search.
I think it is a difficult question since seems that everybody has powered this plane with a Moki 180.
I think I will go definitely with a Brison 2,4. I will post the results later if someone are curious about performance. I think it is almost a perfect combo. The engine is only .75 lbs over what I have already, so my flying weight with a gas engine will be almost 13lbs, which is great for this model.