If you're having problems with the pre-made FitKirbyMetaKnight.pac files I included, this may help.

Take a clean copy of FitKirbyMetaKnight that works in your copy of the game, and insert these files into it.

The texture replaces the default texture within FitKirbyMetaKnight.pac

EffKbMetaknightMachTornado.mdl0 replaces the single .mdl0 file within FitKirbyMetaKnight.pac