I think your original post actually ends the thread. Even guys like Briggs and Marvin Hart had somwe quality wins on their resume. It is Neon Leon and it isn't particularly close.
Marvin Hart Sullivan Corbett and Fitzimons probably all beat him and we know Burns can hence Johnson can and of course Jeffries can. After that weakest would be Willard and Carnera and I’m picking them to beat old Marvin.
Sullivan without a doubt. Post Willard it would be Marciano, Walcott and Ezzard Charles. With the champs between Jeffries and Dempsey being ahead of who came before. Leon is hard to rate cause he got thrown into ongoing traffic and once out of contention he went down to Cruiser.