If it's truly 50yrs old, it would be tin lined... Paul Van Achter didnt perfect the technique of bonding stainless steel to copper until 1983.
You might want to ask about their thickness. You really want it to be 2.5mm+ (2mm is acceptable)
Edit: looked it up... The Revere 'copper' pieces are copper coated clad stainless and of thinner gauge. It's not true copper cookware so ignore my above post.
Revere introduced the Paul Revere Ware line in 1967. Produced only at the Oneonta, AL plant, the copper/stainless steel material it used was made in-house using a high temperature, pressure-bonding process, not the traditional Revere electro-plating process. Designed as much (or more) for visual appeal as for function, the solid brass handles were attached with rivets welded to the bodies (producing a riveted handle with no exposed rivet heads on the cooking surface).
Initial production carried "Limited Edition Collection" stamped on the undersides of the handles while a stylized Paul Revere "signature" was later added to the underside of each piece. This combination was designated the "Paul Revere Signature Collection" when the handle imprint was removed. A special issue commemorating the American Bicentennial added "1776-1976" to the hallmark."