Louis most likely would. Dempsey definitely could. Tyson would, Frazier definitely could, and Marciano has a chance. Marciano would have the least chance of the swarmers in my view. It's about the explosiveness and speed. Dempsey and Tyson just match up much more aptly to score an early KO or even wear Wlad down than the attrition swarmers like Marciano and Frazier. Although I'd favor Frazier, and still give Marciano a legitimate shot (Without favoring him though).
And Duran. And Camacho, with the help of a bat or brick. Some people shouldn't be messed with on the street.
It is fairly reliably reported thet Young Griffo KOd Jim Corbett in a street fight. There is a primary source on that one.
If Duran's prime was in the late 90's, with superioor diet and nutrition i see him making the HW and capturing an alphabet title, its not such an impossible task considering how many titles there are. He meets a green Wlad and clocks him? Who knows. Wlad has the size advantage but Duran's style is all wrong for Wlad, who is vulnerable to infighting, in which Duran excels.
The 2 guys in my avatar pic are IMO a dead cert to stop and probably KO Vlad - I would be interested to know how many very good sub 6ft fighters Vlad has actually fought in his career - and who could really punch?? - I'd dare say not many?? So highlighting Brewster as the smallest man to have actually stopped him is not really evidence of anything other than evidence that anyone as good as Brewster could stop Klit. Interesting question though all the same - but simple answer is Vlad just doesn't have very much confidence in his own chin - and that more than anything else is evidence that anyone with a big big punch is going to have a great chance. :good