Fourtrax 300 oil pump and crankshaft gear.

Im pretty new to posting in forums but I need some help with a 1998 Honda fourtrax 300 4×4, engine was running fine until lately the clutches started slipping. Figured I’d go for a ride a few nights ago and I heard a loud rattle where the clutch cover is so I shut it off and pushed it home. Removed the clutch cover yesterday to find gear teeth at the bottom
Of the case and a large section of a small gear. I pulled the clutches and oil pump to find out that the oil pump gear is stripped of most of its teeth and there is a small gear on the crankshaft that turns the oil pump that is missin a large section. I can pull it off the crank pretty easy. Now my question is, is there a way to pull that same gear off of a parts engine and put it on my engine. And replace the oil pump. I did find what looked to be the same gear but it’s for an 86 Tex 350 motor and they look basically the same. My bike does have an 18% gear reduction if that has to do with anything. I’m just trying to keep from having to replace the crank