An excellent scale to play over a fully altered dominant is the "super locrian" or "diminished-whole tone" scale. It's another way to think of this scale.
The first half of the scale is diminished, the 2nd half is whole tone.
For C alt the scale is C Db Eb E Gb Ab Bb C.
Scale formula is: Half, Whole, Half, Whole, Whole, Whole, Whole
As BigAl said it is the 7th mode of the Db melodic minor scale. However, it is difficult for me to think of it that way. I have to think of it as a scale in C because of the way the chord is notated: C alt (which means C7#9b13). That way if you're wanting to play it in Ab you don't have to think of it being the 7th mode of the A melodic minor scale. You can think of it as an Ab scale with this pattern: HWHWWWW.
From the last 2 chords of the OP:
Db/ Db F/ C Eb Cb This chord contains both 7ths, probably a typo. I'd play Db/F B/E A Db (Another fully altered chord)
Gb/Gb F/ Eb Ab Db which has voices leading to Gb/F Bb/Eb Ab Db (Quartal voicing of Gbmaj13)
Not trying to be antagonistic BigAl. This kind of stuff is what some talented musicians are PAYING for.
And its free here in the Organ Room. Play on.
