The early MDS engines in the US had a carb that was junk. If you replaced the carb, you got a good engine out of the deal. MDS eventually replaced the carb with a slightly better design that some folks get working just fine. But for something that might have been gathering dust at the LHS, I'd probibly avoid the engine.

HP numbers for model engines are garbage. Just ignore anything said by any engine company about HP produced by their engine. They get those numbers by using an overly small prop and winding the engine way up to some seriously high RPM. It doesn't reflect the engine's torque curve, which is a more useful thing when it comes to actually moving airplanes around.