The Mephisto Waltz
(1971)
Alan Alda plays a classical piano player on the rise who befriends a famous player himself who's at death's door. Unknown to Alda, the guy is a satanist, who arranges to have thier souls switch places at his death, so that he can be young again and continue to play piano (thus needing a skilled piano player like Alda to switch bodies with).
