RE: please identify this engine
I'm a big fan of conversion engines myself, for many reasons, quality being one of them.
The Ryobi is neat, because with it's rear exhaust and intake, it fits a narrow cowling like on a Mustang or a Tiger Moth biplane without having to butcher the cowl and have the unsightly muffler on the outside.
I have a Tiger Moth with a Ryobi, and cut the cowl only for cooling holes. Looks great and the Ryobi flies it just super.
AV8TOR