I'm in the camp of supporting your decision to re-theme a game you love but are unhappy with its current aesthetics.
I too, am in the same situation. I picked up a Gottlieb Team One Pinball and really enjoy the gameplay and rules, however, the artwork is horrible. Considered fairly rare, with lesson 600 or so produced, it's in fine shape. I struggled with the decision to re-theme, but decided to move forward when I realized that each time I played the machine, I thought about how much more I would enjoy it if the artwork appealed to me.
Move forward, re-theme it, and share your vision with others. Looking forward to seeing what you come up with.