My '72 Atala has nicely chromed lugs, seat cluster and frame/fork ends, and paint on the rest. It seems that was what Italian factories in that era. The paint flakes and doesn't adhere very well - it appears that there's nickel plating on most of the frame underneath the chrome and up the tubes. I never cared enough to do anything other than patch with laquer. I ride it.
I know that chrome is very hard, not so sure about nickel. But I imagine that it would be hard to get a good paint shore line with either without some aggressive sandblasting.