If you want your motor to last, i would replace it.
1. Hot rod crank
2. Cometic gasket kit
3. All new seals
4. Yamabond 4 for cases
5. Your choice pistons(anything by wiseco)
6. Needle bearings
When the shop does the bore, they will let you know what size to buy or you can order them there. You should only pay about 40 bucks per cylinder to bore, chamfer, and hone. Otherwise your gettin ripped off.
Or if you are just gonna hone, (which i do NOT recomend on that old a motor), just take the head off and buy the same size piston thats in there. (its stamped on the top)