What is that peppered black crap on the chain, clutch outer, pressure plate? Did the fiber weld to the steel plates? If not there, might as well clean the debris, check the plates. While apart, spin the crank nut to see if the clutch outer turns. Spin the main shaft that the clutch center bolts up to.
I'd pull the plugs, see if the plugs look normal or are hammered by the valve letting go and eat the piston dome, peppering the spark plugs.
It's either the top end or bottom end, if clutch parts show good.