Watch this video.
https://www.youtube.com/watch?app=desktop&persist_app=1&v=iYpzeVNcEG4
Jaffro makes very good educational videos. He shows how you'll be measuring the bores for being out of round. If they're out of spec, replace the liners. New liners, bored and honed to match your pistons, with new rings, and new bearings would be "rebuilt" as far as the bottom end is concerned. If your valve guides are in spec and a lap brings the margins to a good surface in the right spot, just replace the valve stem seals and call it done.