Lee might have been, and probably was, one of the greatest marshal artists to ever live.
However he was not a fighter, at best he was a performer. Comparing him to someone who fights for a living and has perfected their ability purely to fight other people into submission, is ridiculous.
He is one of those figures who has been turned into something more than real, which I feel takes away from his actual accomplishments.
Saying that however, at his peak against someone in his weight class? Yeah he would probably destroy them. His real strength lay within his size compared to his power, remember he weighed less than 11st and was only 5'7. Put him against someone like Tyson