I've been messing around a lot with that chord progression from a week ago today, but I think I've finally found a B-part I'm happy with. Transposed it to Am instead of F#m as well. It surprised me a little, when I was hunting around for ways to get from the Bb in measure 21 to B7 with two bars between them, how satisfying it was to go from one chord to another rooted a tritone away. Kind of throws off my sense that one is supposed to be more or less substitutable for the other. Or maybe that's just pairs of dominant sevens.
Am | F | C G/B | Am Am7/G | F | G | Am | E7 | Am | F | C G/B | Am Am7/G | F | G | Asus4 | A7 | Dm | G | C | F | Bb | E7 | Fmaj7 | B7 | Em | Bm | C | G D/F# | Em | F | Bm7b5 | E7b13 E7 |
There was some other little bass groove I'm still not really capable of playing with just my left hand too well... the rhythm was 1-2-1-2-1-1 eights alternating A-(DEA)2-A-(DEA)2-A-DEA for one bar and then Bb-DEbG for the other.