ORIGINAL: Magna
I want to fly gasser on this one, will Zenoah G26 fit? The power is about the same as 120 FS.
This review is for the Hangar 9 version but it discusses gas engines in the model
http://www.modelairplanenews.com/reviews/pt19.asp
The GP & H9 versions were similar size, so some of the info could possibly apply.