Havik could easily change alignment, it would be enough if Shinnok sets up one rule and Having gets the good guy.

Shao Kahn would be very different and complex. But maybe if he wasn't in the army of Onaga he could be a good guy.

Real simple for Havik don’t even have to change his personality. Shang Tsung wanted to control all timelines and Havik hates control.

As for Shao it’s said in the original timeline he was outworlds protector so in his timeline he just never became greedy and power hungry