Last night I played it through to the end without skipping (but with save state abuse - f*ck level 6!), and the ending appeared like it should. Hopefully that ain't gonna be a problem.
The tunes have a few problems though:
1) The end level and high score tunes are chopped off at their ends. The tracks themselves go silent and have a couple seconds of nothing at the end (it's not the game stopping the track too early), so the only way to fix this one is to find the complete tracks or recreate them.
2) Tracks 3 and 8 are almost identical (same song but a tad different); and while this isn't a problem per se, it is an opportunity. Track 3 is used for stages 1, 2, 4, 5, 7, and 8 and track 8 is used for stages 3 and 6, so a new track could be substituted so we don't have to listen to the same song in every stage.
3) The title screen and intro cut scene are silent. This also isn't exactly a problem, but it sure does suck.
I didn't want to involve anyone else and risk wasting their time on the first outing, but none of these things can be fixed by me. Any suggestions?