I think you've got it. Basically, since the notes in the Progression, when arranged from C onwards, give you 1 sharp, the F#. The only (major)scale with 6 naturals and 1 sharp is Gmaj. G-A-B-C-D-E-F#-G, following the wwhwwwh pattern. So, in Theory (which is exactly what we're talking about), you could play a G major scale and it would fit throughout the song, though it might get a little repetitive. Other scales would work, but they might have tones that don't fit the sound/style you're trying to achieve in your solo. If you want lots of dissonance, play whatever you want, play a C#maj, be my guest. Different intervals will give you different sounds. I think of it as constructing a scale with not only the notes in my major scale, but also with the notes of the chords.
The chords in the song contain the notes in the G major scale, and if you should decide to play something different than G major, like C major, you'll end up with a different scale, and a different sound. The notes in your lick would then contain G-A-B-C-D-E-F -F#-G, which would create a little dissonance, but you might want that. It all depends on genres, style and whatnot. You wanna keep it happy, then keep it in Ionian, or go darker, play some Dorian. Knock yourself out.
Those are my thoughts.