I wouldn't bother with Superboy at all. He's not as important to who Superman is as a character as Robin is to Batman, for example.
Maybe some of his storyline (a clone of Superman manufactured by Lex) could be used in a sequel in perhaps the creation of Bizarro.
"But that's the thing about Batman. Batman thinks of everything."
"There's always a way. When the odds are impossible- do the impossible."