James Toney is one hell of a boxer but I dont think he quite compares to Tyson.
Tyson was the Heavyweight Champion when Boxing was the most famous it ever was and unfortunately, this embellishes (often inadvertantly) his credentials and skills as a boxer.
Tyson, although explosive and very powerful, is not nearly as skilled of a boxer as Toney is.
As a matter of fact, Toney would outwork Tyson, land more all purpose strikes, and utilize supreme footwork to frustrate Tyson and make him predictable (it would be a boring fight). I pick Toney over Tyson 8/10 times.
Now Hopkins on the other hand, a very smart fighter, methodical, tactical, with excellent conditioning; his length and reach probably wouldn't hurt either.
Although his attitude isn't always the greatest, I think a younger Hopkins would have more potential than the likes of Tyson or Toney.