Your top ten, whatever it is, doesn't exist, never did, so any fight they were involved in did not happen... Simple way to look at it is Ali, Louis, anyone you have in your top ten were never born..., assess the remaining fighters....
Interesting idea- doubly interesting for me since I don't keep records-based lists. So, having settled on a top ten, my alternate universe one, presuming those ten men didn't exist, would be: Johnson Liston Jeffries Patterson Tunney Fury Charles Dempsey Bowe Klitschko V. I wondered whether Ibeabuchi might not have had a record good enough to permit his entry just based on his wins over Tua and Byrd. I would probably choose him over Norton who would be left with only Quarry and Young for top-flight wins. Baer is indirectly impacted by Schmeling not having the legacy-enhancing victory against Louis. In anyway, he and Braddock took a bump when I remembered to put Johnson and Jeffries in. I tried to predict who would emerge as the most dominant in their respective eras, but didn't go so far as to imagine fights that didn't occur in reality (no Schmeling deposing Braddock, for example).
Actually, I forgot about Usyk. But I factored in his exclusion, if you can follow, into Fury's placement in my list for the alternate timeline. I have eleven people in my top ten! Holyfield just entered the conversation, and Bowe's stock rises. Johnson Liston Jeffries Bowe Holyfield Patterson Tunney Fury Charles Dempsey