piston COULD be reused with new rings.. and a hone job on the cyl. me? i'd get the naa cyl.. oring and washer.. and hone the cyl good. the oring is fat and holds up good even if the cyl hole opens up a lil on honing to smooth it.
your call. rings are cheaper.. will likely seal a lil less on a worn cyl.
remember under the cyl is a long and 2 small gaskets.. then the top cover gasket.
use no goop.. go on dry and clean