I just got done rebuilding my top end and i spent about 300$. I had to get a new piston, bore the cylinder, replace crank bearings, rings for piston, and head gaskekts.
To do it right, piston,cylinder bore,wrist pin bearing,crank,crank bearings,all new gaskets. That's a total rebuild, if your planning on keeping it it will be worth it, it will cost around 500 if you do the work
i have had to split my case about 2, 3 times and everytime i hadto take the seal off. So make sure everything fits before you put the seal on and screw it together.
I rebuilt my top end which was a high compression gasket kit, piston, rings, wrist pin and bearing and the cylinder bored for around 200 including a new oem grade clutch kit.