Seeing the crankshaft is not the orginal,My guess you have a clearance problem,maybe to much end play,and hitting connecting rod,block,any chips in oil.
Not to beat this to death but I had to cut .030 off the domes of my egge pistons just to get .050 in the chamber. I cut them from .030 in the center to .000 at the edge reshaping the crown.
I can't think of anything else exept maybe to check the thrust on the crank and cam........