I'm reading Little Man, about Meyer Lansky. I appreciate it because it's a history book about the Eisenhower era (and the post WW1 era as well, there's a significant attention to detail about Rothstein as well). The book is about one ethnic group, rather it's about Meyer Lansky and who he was: the myth vs reality.
It's my opinion that Lansky operated effectively as a Costello family capo.
"Little Man - Meyer Lansky and the Gangster Life" is the best, and best researched, gangster bio ever. Costello was a Lansky ally and business partner, but Lansky never was a capo in his family, nor could he be. His Mafia partner and protector was Vincent (Jimmy Blue Eyes) Alo.