Brandos career had peaked, then ebbed and nobody wanted to work with him.
...
I think I read that the studio wanted Ernest Borgnine for the role. Can you imagine?
Actually, Borgnine could have pulled it off. Think of him in 'The Dirty Dozen' and not McCales Navy. He was Italian, (a Coppola requirement) as well (Ermes Borgino).
The Don was one of the most coveted roles at the time with Kirk Douglas and Danny Thomas actively pursuing it.
“I think I read that the studio wanted Ernest Borgnine for the role. Can you imagine?”
No harder to imagine than IIRC, Eddie Murphy’s role in Beverly Hills Cop originally being written with Sylvester Stallone in mind.