It's fun to write tunes on other tunes - for years I tried to write something decent on Body and Soul changes, and it's real hard, though I did manage - I also recorded something with Rudd about 15 years ago based on Tea For Two - though one reviewer thought the head was "too fussy" (he may have been right). I also had an interesting encounter with Johnny Green, by letter, discussing a tune I was writing based on the changes to Out of Nowhere (he wasn't happy that I wanted composer credit).
I also, on my last CD, on one tune, used the bridge to I Want a Little Girl, which I've always liked (chords are I-IV-VI-II) -