What would happen if Renown and Repulse replaced Hood and Prince of Wales against Bismarck?
Short answer
The British pair would be somewhat faster but face an unfavorable direct fight. A variation retaining Prince of Wales makes shadowing Bismarck and calling in reinforcements the more attractive course.
Notes
Replacing Hood and Prince of Wales with Renown and Repulse would make the British force somewhat faster overall. It would also put one modernized and one unmodernized battlecruiser against a battleship and cruiser, an unattractive direct fight for the British. A separate variation replaces only Hood with Renown or Repulse and retains Prince of Wales. Shadowing Bismarck and calling in other forces would offer a way to exploit speed and maintain contact. Even a victorious Bismarck could suffer enough damage in a fight to make avoiding the British force preferable.