Taking HW as being above 200lbs I'd choose: Lennox Wlad Wilder (crap puncher but very heavy handed) Tyson (underrated right hand, though it was often thrown a an overhand) Bruno/Rahman/Joshua/Foreman (all hugely heavy handed, though not so proficient at landing their shots)
Hasim Rahman had a huge overhand right when he could land it. In raw power one of the hardest shots I've ever seen. Better than Shavers certainly. Trouble was his feet were stuck in cement and he could so rarely land it against the top guys he fought.
