I've owned two of the Zenoah G62 engines. One was installed in a Patty Wagstaff Extra 300 and the other is currently being used in my Great Planes Super Stearman 1.20. The engine in the Wagstaff is "box stock" the other is somewhat modified for use in Reno Pylon Racing, AT-6 Class. Both engines are super dependable, easily starting and running like a top.
All in all, Zenoah makes a very nice engine. They are tough and reliable, but they are a bit on the heavy side as compared to similar sized engines.