How cool would it have been if....

The Evil Superman was actually Bizarro.

This would be a cool way to introduce Bizarro to the film, and make him look deadly, rather than the joke he is often portrayed as.

The movie could make you think that Superman went bad, but it is actually Bizarro framing Superman, and ruining his reputation. The final confrontation in the junkyard could have been the same, or even have it that Clark becomes Superman, and have Superman fight Bizarro.