Help for upscaling GKar 97SE and generally fixing problems with this release

Hi,
i’m trying to upscale the first Special Edtion trilogy from the GKar release.
First thing was to fix the slightly wrong aspect ratio, which was easily to do by using my 2004 DVD as reference.
But i applied the fix in the last step at upscaling.

Also the image is very flat and sometimes dark.
I tried to add a bit of saturation which is okay for me.
Doing more will make the MPEG-2 compression artefacts more visible and make them strange colorful.

I cropped not the complete black bars from the video, otherwise it will crop parts from the alien subtitles.

My main problem is the upscale.
I tried Lanczos and Super Resolution and adding a bit of sharpness.
But i only had to do a very slight sharpness, otherwise it gets really blocky.
With 1920 width it still looks very bad, but with half size (960) it looks decent.
Anyway it’s hard to see a difference between picture quality.
I have to think about it.

Did anyone has experience with upscalers and can help?
Are there any recommendations with blocky unsharp MPEG-2 recordings?
I saw Topaz AI upscaling for example.
It looks clean, but also unnatural to me.

Other issues with GKar is:
In some scenes there is dirt on the picture.
And it’s unsure if it has the original german 97SE intro crawls.
In TESB im sure that’s is not the 97 one, because it has the fisheye- ,Krieg der Sterne" logo and after the first scene change, the black bars are out of center due from a different scan.
Otherwise im happy with the release and very thankful, that it was captured.
It reminds me of my experience with the Special Edition in german TV.

Planned outputs will be:

1. 1920x870 slowed down from 25 to 23,976 fps, 2-pass H.264 4:2:0 (Placebo preset + Film tuning + Blu-Ray compatibility) ~7,9 GiB to fit on DVD-9 + stretched FLAC Audio
2. 1280x580 slowed down from 25 to 23,976 fps, 2-pass H.264 4:2:0 (Placebo preset + Film tuning) <4 GB to fit on FAT32 devices + stretched AC3 640 kbit Audio

The top screenshot is always the original and the bottom one is the result.