Hangar 9 calls for a .60 to .75 two stroke. Do you already have the 55AX? If so then I would say try it, but I wouldn't buy a 55AX for this plane. I imagine it will fly the plane, but I can't say I've ever heard anyone be thankful they have a smaller engine than what's recommended. Usually people want something even bigger. And there's that saying, "There is no replacement for displacement" which I believe is true.

I'm going to be using the 55AX on the 40 size model of the same plane.