You know, 60 years wasn't bad, was it? That's almost as old as I am. I would recommend using Schedule 40 PVC-DWV under the slab this time. It will outlast any other material including copper, which is subject to electrolosis and deteriation. The PVC also costs about 1/4 the copper price. Be sure you use Primer and PVC cement according to the instructions on the cans. Don't let anyone put "universal cement" off on you, it is strictly impossible.