My Space Shuttle came with an overlay. The quality of the overlay was great as it was done by Ed Chueng who also worked on the reproduction playfield. The problem was the person who put the overlay on did a shit job--and that's being kind. I finally bit the bullet and swapped with a CPR Space Shuttle pf. Having owned both on the same machine, I can tell you the look and feel of the game is much different.

All playfields have varying tolerences. For example not all keylines align with inserts 100 percent and this varies within the same game. So the fundamental problem with overlays is that one size does not fit all. You will get inserts that are not aligned and partially not lit. You can't expect perfection.

Overlays may provide an alternative if there is no repro pf made and the cost to have someone restore it is way over your budget. Keep in mind though, the process is still labor intensive (if you do it properly) and not cheap. I think the SS overlay was close to $200, but again that was a high quality overlay. Adding to the cost is having it clearcoated, which I've heard conflicting reports as to the reliability. Personally I always choose to restore the pf no matter what shape it is in, I've seen enough artwork that can be redone with an airbrush and/or water slide decals that I would never think to use an overlay.