By 1983 the theatrical landscape had changed significantly from how things were circa 1977; stereo became the norm, where once mono was the lowest common denominator that had to be supported for widest reach. What you are hoping for really may not have officially existed as a mix unto itself, as the need for it had subsided and Lucas was very progressive, always pushing boundaries for video and audio quality (until he apparently lost his mind), never happy to be held back by artificial limitations. If you really want to watch the movie in mono, that is something you’d probably have to do on your own by just down-converting the audio and–very easily–muxing it into your mkv file; just know that if your intention is to have a theatrically accurate experience you won’t find that with mono for this film (unless you want to replicate a rundown '80s theater making do with a stereo film playing on their mono setup).

But really, it isn’t the amount of channels of audio that people are looking for with Star Wars films when talking about mono vs other mixes, it is about watching the film with subtle audio differences between the mixes. That definitely was the case with Star Wars, and I’m not sure but may have been the case with Empire (more so the early 70mm cut, if you want differences), though with Jedi there doesn’t seem to be a holy grail of slightly different released audio out there. But, if you find you’re still dead set to find mono for Jedi, then you’ll have lost the original point of wanting different mixes and be doing it for the technical difference of how many channels, rather than for the historical content.