Pistons are bore look fine from here. The crowns will clean up ok and that minor rust pit in the liners is low enough to make very little difference - unless you are thinking of going larger bore anyway. If you go much larger on the bore you may have to consider a 650 top end to get enough air in.
But unless that's where you want to go, try to use what you have. Shops like my guy in Australia 2 decades ago or Pete Fischer at Powroll ( I think that he may have crossed the rainbow bridge too) those guys used to be set up to line bore the head and cover to take split bronze bushes. See if there's anyone that can do that.
The cam and bearings don't look too bad depending on your planned next steps. They show wear and rust pitting and so on but are probably usable without losing much power or longevity. Of course it would be better with all new parts, but you might be surprised how worn parts can be before they absolutely have to be replaced. That's why I tell people not to pull a crank out if the bike is running just fine. Once you see wear and pitting, you cannot unsee it. If you want to replace/repair parts and have the budget or a good source of cheap replacements, don't be too much of a perfectionist.
If parts are way out of round or lost oil pressure or compression is low, that's different. Oil seals on the guides? Go for it. Wear in the guides? measure it and see if it's still in spec. I like everything in a race motor or a bike I am selling to be first class, but there are limits for a reason....
Irk knows what bits go together on those motors and might have some ideas.
www.dotheton.com
