Quite honestly, I definitely don't want to see any spaghetti westerns in 3D other than those designed to be screened in 3D. One of the great things about the best spaghetti westerns is that the directors really used the screen like a canvas, creating fantastic compositions. The Italian directors tapped into a monumental artistic heritage and you can see the influence of Italian opera, literature, sculpture and painting.
The best spaghetti westerns are literally packed with fantastic, interesting compositions which have been created with a two-dimensional screen in mind. The best directors are not simply giving you a window into events, they are representing those events and using the camera to flter the action for the audience. It's that which is really interesting and demonstrates the supreme skill of the film maker, and I don't want to see it fucked with any more than I want to see the artworks of Leonardo da Vinci or Michelangelo fucked with. As soon as you put one of those films into 3D it's distorted in such a way that you start to lose sight of the director's vision for the film.
I'm not against 3D per se, but it has to be used right. Retrospectively rendering great spaghetti westerns into 3D is not a good use of the technology in my opinion.