Actually, the major wear is the wrist pin hole through the piston. I've seen them with so much slop, it is a wonder the pin didn't fall out---yet.
Starting in 1961, the wrist pin diameter was increased, and the same bearing as the big motors was used. The parts can be retrofitted to older motors but you have to replace pistons, wrist pins, circlips, connecting rods. and wrist pin bearings. You get a much tougher powerhead when done.