This is really great, definitely nice. I think that instead of just bookending (even though that's a good idea), you could maybe touch on another part of the song during the improv, for you or him or both. I also thought that the section from 3:25-5:55 had muddy parts, where you and the piano were fighting for attention, but maybe that's just me. It was also very long.
However, this is exactly the kind of thing I wanted to do in high school and never got the chance to, so I have to give you mad props. plus, your set up sounds really nice. what kind of studio do you have?