I'm assuming Tarantino lifted the plot from...
..."Comin' at Ya!" (1981), which was a Spaghetti Western and the first major release with 3D effects in 17 years. Being successful at the box office, it paved the way for 3D flicks of the early 80s: https://www.imdb.com/title/tt0082193/?ref_=nv_sr_srsg_3
The style & content are reminiscent of Leone's "The Good, the Bad and the Ugly" (1966), but has superior colors, more action and doesn't overstay its welcome. Unfortunately, like all Leone-styled Spaghetti Westerns, the characters are either caricatures (the slaver brothers) or cardboard thin (the hero & his wife), which makes 'em uninteresting. There's barely any dialogue with no verbiage at all until almost the 13-minute mark.
Some people call "Comin' at Ya!" garbage, obviously because of the sadistic brutalities and horrific components (e.g. the rat attack), but there's an undeniable artistic genius to the filmmaking. For its DVD release (2016), the digital transfer was subjected to CGI alterations. The most obvious of these was the changing of some shots to B&W with one or two elements of color within the shot. I thought this improved the film.