I always wondered why Scorsese used this of all names for the character. Does anyone know why Scorsese used it?
Probably because it just has a ring to it. Despite these being Chicago guys, the Gambinos had been in the news a lot in the '90s. So my guess is Nicholas Pillegi, who wrote the screenplay just hijacked Nino Gaggi and made it "Remo", because it just had appeal. Gaggi, Gotti, Gravano, etc were names that were in the papers a lot then.