I have a 1980 xl500s that I am redoing. Took me a few months to get the engine back together and I still need to paint the side covers. My piston was toast but the cylinder looked ok so I was hopeful like you that all I needed was an OEM piston. No such luck. My cylinder was over the serviceable wear limit so I had to go 1st over. I went with a Weisco10.5:1.
My inner valve springs were shot and there was evidence of slight vlave floating ( cacrbon on the top of the piston was scuffed from the valves kissing the top of the piston, luckily the valves were undamaged) Might want to check your springs while you have it apart.
I was expecting my cam bearings to look like yours but I got lucky. Even so I debated about boring it for some needle bearings. I'm sure I'll regret not doing it while I had the valves striped out of the head.
I got lucky, my cam chain is in good shape, but if you have a line on where to get a cam chain guide and a new adjuster Id love to know.