I think Scorsese used those songs because it just takes him back to that time. He seems to avoid the classical pop, the Sinatra, Dean Martin, etc. He'll throw the occasional rat pack number in there but overall all of his mob movies tend to be scored with early rock and roll, soul ballads.

Yes, Turnbull, the scene in Mean Streets is great. Also "Florence" when they're driving to the pool hall. The biscuit song. "Pledging My Love" when Charlie is dancing with that girl after that vet loses it.