Most thread chasers will quickly become dull trying to cut through the chrome on a Campy spindle.

The triangle file will also be dulled by the chrome, but they aren't too expensive, so it might be worth sacrificing one. That takes a fair amount of filing skill to do well though. Good eyesight too, and/or watchmaker's magnifiers.

If the pedal is useless otherwise, then you have nothing to lose by trying I guess. Don't let my negativity stop you, if you have the gumption to try it yourself. It's not like Campy pedals are so rare that it's a sin to ruin one by trying to fix it.

You can also swap in a good spindle from a pedal that was damaged somewhere else, like cage worn out from cleats, or crash damage, as long as it didn't bend the spindle. And those spindles pretty much never bend, they're ridiculously strong! The crank will bend before the spindle will, in my experience.