One sequence which I hope could be augmented would be the Diagnoga scene.
Back when the first revisited was made Ady wasn’t as skilled and the technology to maybe look into the scene wasn’t available for general use if at all.
It played out okay to my 7yr old self back in the seventies but now it’s really obvious (despite Mark’s sterling efforts) that it’s a rubber octopus tentacle and likely the same one that looks crap pulling on Threepio in Jabba’s Palace Cell.
The real problem is the interface between water and the model and any additions that might be made.
It might be possible to film some wormy mini tentacles that come out of where the sucker cones currently are and then join them to the footage, rather than animating them in a computer.
The main problem is when the tentacles get stretch flat against Mark’s chest and look more like a belt than a living creature.
If the tentacles had little millipede like legs they could try to flex and crawl to get a better purchase on Luke and react to being struck and the eventual call to escape.