I would suppose that for the med' The poorest non slave classes could survive to 40s at least, well i would expect only a few of the very poorest would be alive after 50.

It would not surprise me, that for the ruling class of romans, there would be people in their 80s.

These people would me more phiscally active than most of us so i would think they were physically quite fit. and if they were rich enough to have the better diets. I'm sure of 80s for the richest strata of roman society.