I don't think the guys in the photo necessarily have to be heavyweights, either. Accardo and Cerone are the only two we've mentioned so far that could be considered as such during this time period. Amato and DiVarco would have been roughly equals at this time, IMO.

Edit: I changed my mind: I just saw a picture of DiVarco at the Senate Rackets Committee in '58, roughly around the time period of this photo, and he has black hair.