I used to own that plane and it happened to be my first gasser. It flew great and I really liked it. I sold it a year ago to get into other planes. Anyways, I looked at the Fuji engine for it and the folks at Kangke did not recommend that engine because you would have to hack away alot of the firewall to get it to mount properly. Plus, its way too much engine.
I used a Zenoah G26 in mine and it was absolutely perfect. Perfect balance and power. It mounted easily and didn't require any major modifications. I would go with a G26. Also, you could take a look at the Brillelli or BCMA 26cc engines too. I own a BCMA 26cc engine and like it very much. There is definately more of a fiddle factor when you get into electronic ignitions. Even though I own multiple gas engine (all with electronic ignitions), its hard to knock the simplicity of the G26.

If this if your first gasser, go with the simplicity, durability, and no hassle ease of the G26. Mine popped over on the first flip every time and ran about 35 minutes on a single tank. I had smoke in mine and a Bennett muffler.

Do a search for "kangke monocoupe" and you will find loads and loads of info on this plane.