Modify Song Intros with End Bars

I need to replace the first 4 introductory time taps of each song with a copy of the last 4 bars of that song. This modification is required for 12 songs, all in WAV format. Unfortunately, I only have the final mix of the tracks, not the original stems.

Key Requirements:
- Replace the introductory taps with the last 4 bars for 12 songs.
- Work with WAV format files.
- Utilize only the final mix as original stems are unavailable.

Ideal Skills and Experience:
- Expertise in audio editing and mixing.
- Proficiency in handling WAV files.
- Experience in working with final mixes to achieve desired modifications.