You would have to change the air horn on the 920 to match the 930 and then it would work on the 920, also. At least, that is what was talked about here awhile back.
That is where i am currently at. Bought 930 carb & air horn off ebay a few weeks ago. Bought 930 top cover & air filter cover off motorsag last week. Air filter with the carb looked like 288xp filter but was full of crap, i guess that is why that saw was parted out, any rate, now have extra carb if any one needs 1.