Can't imagine how strong he would be if he was taking the same stuff modern guys use. He'd steam roll over everyone.
I think today's Wladimir Klitschko is probably too experienced and seasoned for a the Foreman who fought Frazier. But with the right learning fights and smashing his way through the ranked contenders, Foreman could be made seasoned enough to dethrone Wladimir. That was Foreman's problem back in the 1970s, too many tomato can fights and then got past Frazier and Norton too easily, due to styles really, so nothing prepared him for the experienced Ali.