He wrote the score for the "real" Sacco and Vanzetti", and also (I think) for the Spaghetti western Edisaurus keeps longing for.
The REAL Sacco and Vanzetti? I would say a documentary would be far more "real" than a dramatic movie. BTW, the director of the film you mention, Giuliano Montaldo, is in our film---we interviewed him at his apartment in Rome. It was very challenging dealing with Italian electrical wiring and elevators the size of linen closets.
We use clips from that film in our documentary...it's one of the best dramatic versions of the story, but there were also French, German annd American versions as well.
I don't think Morricone wrote the music for Cipolla Colt, though. A B-movie like that probably would have been beneath him!