If I'm seeing it correctly, it looks like one of those valves broke off and rusted into the valve guide. Not sure how you can fix that, the guide would be destroyed when you try and get the rusted valve stem out???
Will be fun to see what those rusted heads look like after a 48 hour vinegar dunk. Will then probably have to wire brush them down, tap on a few things and see what loosens up. Sand the burrs off the valve tips so he can get them out. If things are stuck yet, back in the vinegar tank again for another 12 hours. Maybe even a 12 hour dunk after that, in diesel fuel too if things are really stuck, that will cut the carbon.
Usually the exhaust guides are the one that are wore enough to need attention. If he is lucky he could knurl them and go again.
Let's wish him luck and see what he can do with these heads.
A new set of valves solve a lot of problems and help tighten up the guides, if he can get past the rust pitting in the seats.
