This is just something fun, with no other special edits made after initial alignment, here is the opening to The Empire Strikes Back set to the score from the 1950’s Billy Wilder classic Sunset Boulevard.
https://streamable.com/i4yse

(I would recommend at least watching the opening if you haven’t already seen the movie before viewing this mashup.)
ESB video sourced from 35mm restoration thread by poita
Sunset Boulevard audio from https://youtu.be/u2RHPQpSbYI

I don’t have anything more to build on top of this, there is no extended version, but I thought it would be different and could open up some discussion. Maybe others have tried their own soundtrack replacements, what score would really change or suit other scenes in fun and interesting ways?