Nothing is impossible. But that said, things can be rather difficult. I would imagine that such a thing could be performed but it's integrity will be fairly compromised to the point that you're better off getting a new one. This would be even more critical the higher the engine redline is. Correct me if I'm wrong, but for an engine like the 2ZZ, would the cams also have to be of the balanced variety? If this is the case, it's just one more thing that has to be done carefully when repairing.
Not worth it in my opinion since if it fails again, the engine may be less lucky. Not to mention that it would be more cost efficient to get new ones compared to paying to get the old ones repaired as well as they can be.
I know it would be the easier to buy a new one but only one of them is damaged :(
Wouldn't maching shops be able to balance it afterwards? I'm more concerned about trying to fuse them. Not too sure what coating is on the cams and if the mater is easily welded or otherwise..
BTW these weren't damaged because of an engine. It was due to shipping and handling <_<