In my experience with SM cels, you can get distorted
lines/images if the cel takes place in "mid-action." 
That is, if the character is doing something quick which
might also account for the high number in the cel sequence.
The higheset SM sequence I currently have is a C44 cel (so
it's possible to get up there).

Additionally, the touch-up work could have been studio-
done and not a restoration. As for being a fake, I recommend
that you find the cel in SM video tapes. Then, you'll
be able to tell for sure. I would claim that unless it is
a cel of a rare character or scene, why would someone bother
to make a fake?

Hard to say without seeing the cel, though. If you feel 
comfortable enough, feel free to email me personally.

Good luck!

Wendy