Godfather Part 1 and 2, followed by Goodfellas are at the top of my list..
Ya one and two were pretty accurate if your looking for that as well as goodfellas.
BTW, there is a youtube channel by Frank Cullotta where he used to answer questions.
That Chicago outfit was nasty. Dont know how it is these days.
Both Godfathers are masterpieces...I can watch them multiple times and never get bored.