If your computer didn’t spend hours encoding anything, and it only remuxed it, you don’t need to worry about video quality. As long as all the audio is there, and the two videos (crawl/rest) are playing nicely, it sounds like you should be in good shape.
Yeah, but I want an MKV as well, lol (I really don’t know why, I just kinda do). RU.08’s suggestion seems to be spot on though. The file is a little smaller, but I couldn’t detect any difference in quality between screenshots, even zoomed in. I may revisit this by adding in the 1985 LD track though, because I miss Threepio’s tractor beam line. I assume that VHS releases were the same audio as the LD, weren’t they? I remember that line and it felt a little odd when I got my copy of the GOUT when it first came out that it wasn’t there. With that audio track and the 81 crawl, this will truly be the version of SW I fell in love with as a kid.