Assuming that the sleeve had been bored correctly and the piston clearance was correct .
And that the engine had been broken in properly and not overheated [with the chance of a partial seizure ] .
I would look at the conrod and measure it accurately and check that it is not bent and that the small and big ends are parallel to one another .
Blessed are the cracked, for they let in the light. - Spike Milligan
"When you come to a fork in the road ,take it ! When you come to a spoon in the road ,take that also ."