You made a masterpiece, period. The choice to scroll the screen vertically, also without reducing the vertical lines for a taller display, and to open the top border using sprites for the top texts were really perfect and agreeable. The c64 always missed a 1:1 pacman porting, despite it was 100% feasible, and you demonstrated it ! Kudos ! Ok there is room for improving the sound, but I am sure you will eventually perfection it
Uhm that's not so obvious, considering that Namco iirc used a chip where you could specify custom waveforms. The SID has just square pwm, triangle and sawtooth. As for the main opening theme, I think the bass timbre can be imitated syncing two waveforms, or at most with a sawtooth or narrow pulse wave. For the melody maybe a triangle wave, or a slightly low-pass filtered square wave...just guesses, there is much room for experimenting, it's fun stuff :)