Well, after watching an old version of the theatrical cut at a cinema in London, I am going to bite the bullet and buy a laptop capable of deep learning on Black Friday and I am thinking of investing in Adobe Premier Pro, Character Creator 3, and iClone, Deepfacelab, and Lyrebird (or equivalent).

I’d like to create a hybrid cut for personal use. I’m not 100% sure what is missing from the DE compared to the SLV (excluding scene trims) beyond a couple of lines of dialogue on the bridge and in Ilia’s quarters, plus Sulu & Ilia, and the airlock scene.

So my ‘basic’ plan is:

Re-add missing scenes and lines above.
Trim the gap between Sulu’s, “Why it’s Mr…” and Kirk’s, “Spock!”. It’s really clumsily edited.
Digitally replace Kirk’s space suit to match the airlock scene. (I think from memory I need to re-order the scene in Ilia’s quarters to match the SLV?) Replace the Enterprise over the scaffolding.
Insert some additional cloned footage of Grace Lee Whitney to establish Rand in the second half of the movie with additional dialogue (if the Deepfake and Lyrebird results pay off). This is partly because Rand started out as the female lead in the original show and partly because Grace was treated terribly at the time. I lament the fact that she wasn’t more front and centre with the ensemble cast for her return.
The basic would be an extra line for her in the McCoy transporter scene plus some dialogue in Kirk’s quarters.
If they work out OK, then I might also consider a close up on the bridge during the V’Ger flyover (the problem there being the need to establish her arriving or leaving and a spot to put her in for the long shots) and establishing her on the bridge at the end of the movie so that when Scotty and Chapel arrive, all the original cast is in the scene together.
The most ambitious edit would be to add her into the airlock scene, possibly adding an exchange between her and McCoy as Kirk leaves, since that will require a digital avatar.
The really, really, really ambitious edit would be to put her in a spacesuit alongside Kirk and give them some dialogue as they head out to the orifice so that Ilia’s question, “Why have two carbon units entered V’Ger,” can apply to them.

If the Rand stuff pays off, I can consider whether I can add a few snippets of dialogue for other characters. McCoy’s funny dialogue was a hit with the audience in London so I considered if it might be possible to add some extra humour. Possibilities would be a line of sass from Uhura when the men meet Ilia, an exchange between McCoy and Chapel in sickbay based on dialogue from In Thy Image, and Spock’s sass about his presence being essential if McCoy is to remain on board in the final scene.

All the above said, I have no real experience with this kind of editing, so wish me luck. If anyone has access to the SLV files, they would be useful, since my only copy currently is on VHS.