There is a book about Marcello called Mafia Kingfish by John H Davis. I picked it up at a used store a little while ago, havent read it yet though. I think its supposed to be the best book on Marcello, though it also looks like it has a lot of stuff on the JFK assassination.

I havent read The Silent Don either, but from what I understand its the best book on Trafficante. I think the author actually posts on here sometimes.