This fight actually happened, although only in narrative, it was during the Murray Woroner produced All-Time Heavyweight Championship aired in 1967 when Marciano and Tunney were matched in the first round. Many believed that Rocky would not make it through against such a ring savy boxer. Yet make it through he did, but what really made everyone sit up was the one sided nature of the transistorized battle for Marciano won on points and not just close. Rocky, said the computer, won almost every round.
There is speculation that the reason for Marciano's complete superiority was more to do with the fact that of all the extant heavyweight champions involved in the fictitious tourney Gene Tunney was the only one who refused to be interviewed and used as part of the shows that were pieced together to make coherent and almost believable events...This may just be another example however of a side swipe at Marciano himself as there are many self appointed boxing historians who could not, and still can't, grasp that the reason Marciano won all his fights was not because of his opponents deficits but because of Marciano's strengths...Thanks for the posts and allowing me to reply.