Please do a search here for "kangke Waco" and you will find a wealth of info. In particular, there is about a 30 page thread that gives all the info you would ever need. I suggest you read through this, as it contains all the info you would ever want on this beautiful plane. The thread starts out with prototype info from Kangke directly and progresses through to the production of the plane and recommendations on engine and servo, etc. People have used engines ranging from a saito 300t, to brison 2.4's, to ZDZ40's, to zenoah G38's. All work great.

To sum it all up, its a great plane and by all means buy one, but you may want to use the search engine here on RCU as a great tool. Mine was powered with a ZDZ40 and it had smoke in it. There were no balance issues whatsoever with this engine.
it was a great plane, and I sold it to purchase my 28% extra.