From the Stanley Kauffmann's review: "Like Kurosawa's The Seven Samurai and The Hidden Fortress, Yojimbo can be compared with a good western. (There is a rumor that Hollywood is to remake it as such.)" (September 17, 1962)
So how did Cinecittą get there first?
So you've discovered that it was Ronald Lubin who wanted to buy the rights to Yojimbo?
Sounds like you just did This guy: http://variety.com/2004/scene/people-news/a-ronald-lubin-1117906497/What's your source? Did you find it out in the Kauffmann book?
Walter Hill did make "Last Man Standing" but that was over 30 years later.