Clay bar on original paint?

I'm doing some restoration work on this car now. It sat in the same spot for about 22 years. It was under a carport, but not covered on the sides.

Here it is sitting where it did for 22 years. It looks a LOT better here than it was.




Here it is in my shop after it was towed out to the house before my son cleaned it up.




Another shot to show the oxidation. It was BAD.




Here, this is after he washed it, clay barred it and then hand waxed it. We could have buffed it but did not.



Another clean shot.



I know. It's a Chevy. But it's a numbers matching one owner LS5 SS 454 that my friend bought new in 1970 from Dunlap Chevrolet in Macon, Georgia. It's a cool car. Oh, and while this is not the original paint, it IS a single stage enamel that is more than 30 years old. Were it not for some rust trying to come through under the rear window, it would still be very good. The clay bar works well.