Hey Chris
I would recommend heating the valve up and remove, and then use a pipe sand paper or mesh to clean up the solder (you may have to continue to heat the solder and immediately sand to smooth out and remove as much solder as possible.)
Then a sharkbite fitting will work fine (obviously wait till the pipe cools)
Otherwise, if you already cut the copper, a copper coupling would work, but would force the valve to be pretty far out of wall
If you have 2″ of pipe left, that is usually plenty of room to push on a sharkbite valve
hope this helps
steve
