Marshall and the Movies

I found out today that for a part that I am playing in the musical “Kiss Me, Kate,” I need to get a gangster accent.  So to get this accent, where else am I turning but the movies?  My initial thought was Robert DeNiro in “GoodFellas” for a very threatening accent, but I’m now thinking that Leonardo DiCaprio in “The Departed” might be good as well.

Anyone else have any thoughts?