I've done my own informal research on the rolled fenders... from the numerous ones I've looked at (only original paint cars), it seems it was far more common for the lips NOT to be rolled.

I was told by the original owner of "El Hemi" (70 Hemi Challenger) that his were rolled toward the end of assembly after alignment when they were rubbing. He worked at Chrysler at the time.
Almost seems as if it was done on a case-by-case basis; not always done.

With my customer's cars, I always recommend not rolling the fenders unless they're positive they were originally, and even then only if they really want to.
The problem with rolling the lip is that the side of the fender above the wheel opening tends to get "soft" and usually gets at least a slight ripple that will need further straightening work.
This is especially bad on 'Cuda fenders with their less sculpted shape and the narrower lip.

Rick