BoxRec

Physically speaking.
I'm speaking of the eras around when they fought before all the heavyweights mostly became all really big.
Because I think a few of them were actually larger then a lot of boxers who were contenders and even some champions at times
who had fought mainly or only in the Heavyweight division.
(because thats is were all the money and glory is of course).

Archie Moore is the first guy that springs to mind. He was bouncing back and forth between the light heavyweight division and heavyweight divsion for several years. He often weighed well over 175 pounds for his fights. He actually outweighed Patterson in their heavyweight title fight.

Tommy Loughran was sort of like that a while before giving up the light heavyweight title.

Light Heavyweights fought Heavyweights in the eras of the 20's, 30's, 40's, and 50's... And they often DID weigh more on fight night because the majority of Heavyweights were so small -- and there was no Cruiserweight division because it wasn't needed...

But Michael Spinks was the biggest Light Heavyweight Champion... He usually walked around at 200... When he fought Larry Holmes he wasn't giving up a great deal of size and strength... If M. Spinks were around in the 50's he would have been Heavyweight Champion for the whole decade.