Bixby (et al):
To offer a bit more perspective….
Half of “Mind-Sifter” takes place in “regular” TOS Trek-time on the Enterprise, while the other half of the episode takes place in the 1950s—largely in a mental hospital. The Enterprise scenes were “easy” to get; the 1950s scenes are more challenging and still need to be secured.
Although James had a busy schedule, we did manage to grab a quick “Kirk is tortured with the Klingon mind-sifter” scene that helps get our story rolling, as well as a “nice to have you home” scene with the (quickly becoming ubiquitous) “Admiral Withrow” at the close of the story.
The plan is to re-do those scenes with our new Captain Kirk, Mr. Brian Gross. He, of course, also would still need to do all the Kirk scenes in the 1950s that we have yet to shoot.
Lastly, another challenge we might need to face is possibly having to re-do many of the already-done Enterprise scenes involving Dr. McCoy. When John Kelley became unavailable for the episode shortly before the shoot, the role was filled on short notice by Mr. David Sherin. Many of the scenes on the Enterprise involve the dynamics between Mister Spock and Dr. McCoy. If there is hope to include John Kelley back into the episode now that he has become available, the amount of David Sherin footage that would need to be redone is not insignificant. David did a commendable job in the role under difficult circumstances—not only difficult as a production shoot, but difficult for Dr. McCoy as a character in light of what’s happening onboard the ship. After David’s hard work, it would be a shame to lose his performance. (Personally, I think our fans would just roll with the punches—like they have with a Lieutenant Saavik played by two different actresses--or our own series of three Mister Spocks. I don’t really think it’s a bug; it’s a feature.)
“Mind-Sifter” seems to have achieved some level of popularity with fans familiar with Shirley Maiewski’s short story from when it appeared in the old Star Trek: The New Voyages anthology book by Bantam Books. But I think seeing the story play out more closely to what the author intended, rather than how the story ended up after being revised by the book’s editors, will also be a treat. Teleplay writer Patty Wright also injected some (necessary) scenes on her own that make the story even more interesting and compelling. (Candidly, further subtle script tweaking might be necessary if roles are now to be assumed by different actors.) But I think just about everyone at Phase II is proud (and eager!) to get the episode finished and out the door for people to enjoy. We just have lots of competing organizational priorities, and we can’t do everything all at once—which is actually not all the horrible a position to be in.
A tweak to your clarifications - the Admiral Withrow scene is actually "they tell me you are well enough to go back to work, prove it to me". It includes some of a very long talky scene with Spock and McCoy from Shirley's original. I wrote it with Kirk being so flippant he was almost insubordinate "just let me get back to my ship already". James played it so heavy, however, I was shaking and crying by the time they yelled cut.
Which bears to what Greg also mentioned. I wrote this script to showcase James' incredible range as an actor - tailoring it specifically to him. So, with Brian taking over the role, I am rewriting the Kirk scenes to better fit Brian.
I only added two scenes to Shirley's story...the Admiral scene and one other, required to shorten the timeline to less than the 2 1/2 years Shirley originally wrote. I also included an element Shirley forgot about, and was rather annoyed she did when I pointed it out to her. Other than that, folks should recognize Shirley's story as intact...James' promise to her, and my promise to her family. (her grandson was slated to appear in the episode)
Here are the two scenes already released. One McCoy/Spock scene (which illustrates what Greg said) and a piece of the torture scene (with big chunks missing to remove extra spoilers)