I have one...it also came out of a Cermark Bobcat.
It looks to be a clone of, or a "blend" if you will, of an O.S. .46FX and a Thunder Tiger .46 Pro. I reminds me of a Magnum in some ways...by that I mean the general "feel" of the machining, and the look of the internal parts...and it's made in China.

It's an ABC (with actual Chrome ) and the engine itself is of halfway decent quality, however the carb was a piece of junk, so I swapped one off an O.S. .46FX that had puked it's nickel plating in it's cyl. liner.
After I switched carbs, it runs well...I have it in an old trainer, and still fly it occasionally.

If your carb will allow the engine to run reliably, then the Eagle should be OK for your Cub...but...I would make sure by test running it on an engine stand first.

Which version of O.S. .40 do you have? If it's an SF or FX you might be better off in the long run using that...