I imagine that 4K83 is going to be quite grainy, so any effects work would need to be re-grained for integration. That makes me think that a cleaner Blu-ray source would be better. I think Adywan is using the 2019 version since the Blu-ray is so bad for this film.
At least with a cleaner, more detailed source, it could always be downgraded for use in a more filmic version, whereas it would be more difficult to upscale low-detail work.
I’ve sent you what I have, and if you decide to use another source I will happily use whatever you provide 😃