It certainly looked like Zod died in Superman II, but originally it wasn't to be so. Donner's take had the de-powered villains taken into custody by some sort of North Pole Mounted Police...or something. I guess we'll find out when the "Donner Cut" DVD comes out later this month.
I don't know if that was Donner footage. I've seen an "extended cut" of the movie that was originally aired on network television many years ago. It included the scene outside the Fortress that had Lois and Superman talking, and in the background the "Arctic Police" were loading the PZ criminals into a caterpillar-tread police van.
Another scene that I liked seeing restored in that same extended cut was one where Clark went back to the hotdog stand at Niagra Falls to pay for the hotdogs that he had run off with earlier.
Since there was a Niagra Falls scene restored, and I think the entire Niagra Falls sequence was Lester's, I doubt this was Donner footage.
Whether Donner is going to use it or not in his cut - we'll have to wait and see!