I think it looks good part from one thing...
What sort of gear ratio are you looking at there?
Judging by the drawings your ratio is way off.
[&:]
Depending on what sort of chain drive you're using you might have to consider using a second set of chain and sprockets to reduce the drive.
Pocketbike chain and sprockets are good as they're small and can be used straight off the bike, but mounting such a small sprocket on a chainsaw clutch can be difficult, if not impossible.
Depending on how the clutch is set up you might be able to do something like this:
That sprocket came from the cam in a dirt bike motor actually.
I'm looking forward to seeing more of this project though.