Chuvalo was a lot more refined skill wise than we usually come to think of him has having, but I can't see him outworking Mercer.
I'm not sure it'd be misguided to say that as far as what a guy means to an era, Mercer is just a decidedly better Chuvalo.
Two of the best chins of the heavyweights. I guess Mercer was better skilled overall, but it would be a good fight. When I think of Mercer, I think of him taking those big bombs from Morrison early in the fight and he didn't even flinch, (and Tommy could hit). It's kind of ironic Holyfield was the first guy to put Mercer down. Guess if you hit someone just right it can happen.
I think that Mercer had the better physical strengths, and his good skill on top of that was really made him go far. If you look at Chuvalo, it's not like he's got the same solid power or strength that his chin is known for.