Didn't know that G.M.Volontè thought that Tuco's part was his. From Diego Gabutti's book "C'era una volta in America", Leone interview, page 108 (translation from italian by yours truly):
"G.M.Volontè didn't like Eli being cast for GBU. He thought the role was just perfect for him. He was wrong. I told him to do a screen test. He refused. He was a star by now after all..I was relieved, I would have given him a thumbs down anyway, since at that point I had selected Eli already anyway."
Also according to Sergio, Clint was quite angry when he learned that in FFDM Lee van Cleef was co-starring. "And he was even more pissed off when he learned that Eli would be in GBU. But this time he was right, as Eli would have stolen the show for any actor. He was a force of nature."
By the way, in the same interview (page 109) he confirms once more that he wanted Clint, Eli and Lee in the opening sequence of OUTIW. Leone: "It was some sort of a childish way to say goodbye to my westerns. Eli and Lee accepted immediately, but Clint flatly refused. He said that a star could not be killed in the first 15 minutes of a movie, the audience wouldn't like it and understand it. So I had to change, since it would have worked only if all three agreed".
Quite an interesting book. In essence, in his interviews Sergio did not think very highly of Clint as an actor, and I'm sorry to say, as a man. I think the same applies to Clint every time he is asked to talk about Sergio and his westerns. He does acknowledge the fact that Sergio gave him the opportunity of his life, but he rarely has a good word about Sergio as man and even as a director. He always sort of dodges questions about SL telling some funny anecdotes, but never really admits that he has learned at least some bits of the trade from Sergio. Or is it just me who feels this way?
?
