It would be a shame if we excluded certain level themes for space's sake. I think a 15-track (or so) album of the first game would be fine--the nine level themes, plus Spiral Mountain, Gruntilda's Lair/final battle, main theme/credits, Mumbo's theme, and maybe Tooty's theme. Give or take.
Then again, it's your concept, therefore your call.
EDIT: Nija'd by Cash, and would you look at that--we said the same thing. xD