Dingleberry or stone block

well you either have to bore it and new pistons
or if that's not in the budget ridged hone till it cleans up then a few strokes with a fine flexhone
knuel the non thrust sides of the pistons
and run it
if you can find a shop with a seat cutter that do a muti angle valve job then all you have to do is hand blend the bottom cut
the cutter takes the place of all that grinding
on bronze or steel guides I knurl and then ream and/or hone even new ones to hold some oil