Right before Adywan’s Empire Strikes Back Revisited dropped he released a 1080p version of the '97 SE for Empire. It’s an mkv and it isn’t cropped for blu-ray, so you’d have to re-crop it yourself. I got it and converted the file using tsmuxer and burned it to a disc. It played fine but it wasn’t letterboxed, the picture stretched all across the screen where the black bars would be. I found a guide to help rectify the issue but I haven’t gotten around to it myself.

Guide: https://forum.videohelp.com/threads/376335-Tsmuxer-Newb-mkv-to-blu-ray-disc

For Return of the Jedi I just used a LD rip, slightly saturated the colors and added a slight amount of contrast and the DVD turned out great. Good luck!