Can you get a reading/label off of the carb? That is, is it a separate carb, such as an A3, etc. (I used that model just for the sake of argument)?? Then you might be able to look up the Carb instead of the engine to get the parts. I realize that this is a rear carb that might have its body built into the engine crankcase but it's worth a shot.
Just my $.02
Bob