Namco NEVER made the art. Ms. Pac-Man wasn't even a Namco game. They may own the RIGHTS to the game, but as far as I know there has never been a single Namco Ms. Pac-Man machine produced.
Namco made Pac-Man and then licensed it to Midway. Someone else made a conversion kit demo called Crazy Otto and sold that idea to Midway. Midway changed it into Ms. Pac-Man and shipped 115,000 upright units.
Then Namco sued the game off of them because it used the characters of Pac-Man and the ghosts without permission.