Tunneys chin is good and forgetting that long count because that was really the only round Dempsey won both times he boxed Dempseys head off Tunney is underrated he was one of the first boxers who had fast feet and could move well around the ring and he only had 1 loss in his whole career against Harry Greb who is top 10 of all time in some peoples list i reckon he has the speed and chin to survive Marciano in a 12 round bout.