This is a flawed premise to begin with and would be better to take an ATG and apply a few tweaks. Someone like SRR was very well rounded and you have a proven pedigree without having to do mental gymnastics to try mix and match fighters from different weight divisions. As someone has stated they might have the attributes but not be able to put it together. It''s not just the physical dynamics it's more about the mental side in terms of will to win and the ability and brains to adjust on the fly is what seperates HOF from ATG.
The 5 most complete fighters I have ever seen in the history of boxing in no particular order are the 70’s Duran, 60’s Ali, Charley Burley, Floyd Mayweather and the magnificent Sugar Ray Robinson.
A couple more outside the box attributes to consider - less in the ring and more out of the ring Fight Anyone, Anywhere - No Bull**** : Usyk Active Fighter : Canelo = regardless of any of other Canelo's crap, it's great to see a fighter who is fighting essentially twice a year.