Question about changes in the Gypsy

[emoult]

I recently decided that since I've been transcribing licks and lines from recordings for a short while, I figured my ears would be trained enough to hear changes so I started with Charlie Parker's recording of the Gypsy. Much to my surprise, it wasn't too difficult picking out most of the chords. However, in the 2nd ending of the A section I ran into what I heard as: |Cmaj7 / F-7 Bb7| Cmaj7 / E-7b5 A7alt |
I was wondering if the F-7 Bb7 resolving to the Cmaj7 is a valid progression. When I play along with the recording, it sounds good, so I'm thinking there's a more conventional way of voicing the F-7 and Bb7?
If I'm way off base with those chords, I'd prefer no one told me what they are directly, maybe some helpful hints will do.