RE: Which engine??
I am in the process of finishing a GP 40 Corsair....tried to work in the OS 70 four stroke...anyway it mounted, it was just too large for the plane ...it always looked cobbled up, and the muffler was a real problem.....went with an OS46 and a pitts muffler...all inside the cowl, and a neat installation... any 2 stroke up to a 53 would work fine in this plane...i know a four stroke sounds more scale, but.......