Yes the engines would fit no problem in the H9 B-25. They suggest Evo .40NX glow engines. The Evo 10cc engine is really the same size as a .46 to .56 size glow engine. The .40NX is in that same size range too. It is a drop in replacement for some of those size engines too. The Evo .60 NX is the same engine as a glow version. You might want to use a Pitts muffler or something that fits inside the cowls more though, but you don't have to, if you don't mind the mufflers sticking out more. Your biggest hassle is the ignition CDI unit and where you are going to put them. You might have to get a bit creative and imaginative for them. Other than that the engines would work fine.