I remember Ali stating that he was hit so hard that it actually shook his kinfolk back in Africa. Cant remember who he was talking about though.... But it's funny
You know, many people think Shavers, or heavyweights in general should be out of the equation when determining power p4p. But look at it this way. Julian Jackson will probably be the most popular name in this thread. He fought at 160. Earnie Shavers was probably about 210 at his best. That means he had about 30% more body mass then Jackson. Do you think that Shavers, as a heavyweight, punched 30% harder than Jackson, who was a middleweight?
Julian Jackson, the guy was a monster puncher, sometimes he would hit an oppenent with his right hand and just would walk away before you even hit the canvas. He was the Barry Bonds of boxing, his right hand was homerun.
I like julian jackson, and prince naseem (didn't have the boxing skills to beat barrera but for a 126 pounder he could bang), wilfredo gomez another small guy who could bang.
Of guys in recent memory, Julian Jackson, Khaosai Galaxy, Gerald McClellan. Can't really go before the late 80's though.