Good luck with your project!
I don’t want to discourage you, but be aware that you’ll face a lot of issues, such as :
- you’ll have to previously define what is “its original state” (there is a lot of topics about this single question on this forum, and there is no easy answer)
- a single LUT probably won’t work, since the 4K was regraded on a scene by scene basis (so you’ll need several LUTs)
- furthermore, it seems that the new 4K version was retouched with Power Windows: some parts of an image have been regraded differently than other parts of the same image (see ChewieLewis’ message about this question)
The best way to watch the original film in their near-to-original colors stands probably in the 4Kxx, the TN1 or the Despecialized Editions.