I can't say I think they had similar styles. Cerdan on film is a come forward slugger. Benvenuti a boxer with a punch. Normally Benvenuti lets the other guy carry the fight to him. Benvenuti has by far the better resume as much of Cerdan's career on the world stage was lost to WW2. So on that basis Benvenuti is the obvious pick. But I think Cerdan looks better on film. So a pick 'em fight. My money would stay in my pocket, but if forced to choose, I go with Benvenuti as more proven.
Benvenuti would knock Cerdan out. Benvenuti was huge compared to Cerdan even at 154, which was Benvenuti's prime weight. With his reach, skills, and power hed chew Cerdan up on the way in.