Bad rings, for me, have always spat themselves out. Then it just keeps running slower and slower and slower until pedalling is faster, and eventually is the only sound I hear, as I pull into my yard.
I'd hope for a ring problem, but I'd bet on the tranny or connecting rod. I'd think for a clunk sound, prob'ly not bearings, unless they just fell out somehow, into the crankcase.
I feel for ya, but alot of us have been there!