[Lynn]

The valve: no problem. Drive it out from the top and put in a new valve guide.

The stud: Depends on how deep that crack runs on the stud boss.

It may be possible to fix, but the question will be; is it worth it?

If I were to undertake fixing it, I would try to pry the pin out (in your first pic, looks like just enough room to get a small screwdriver in at the bottom of the pin and force it back out far enough you can get a pair of dykes on it to remove it. Have the head machined for screw in studs. Magnaflux to see if you got all of the cracked part machined off. If not, COULD weld and re-machine but now you are getting into serious money. Unless it is a REALLY rare head, you are miles better finding a new casting.