The width of the corridor at the junction can be estimated in this very shot
- the man walking past is not too different from Shatner and his height is approximately 75% of the corridor width (the extremities of the struts), ie 8'. Whole numbers were used in TOS (and other set plans I've seen) as that made it easier for the carpenters and set builders, so I doubt we would be looking at 7'7" or 7'10" for example.
I've stated my belief that the Probert ship (as planned) is irreconcilable with the movie Enterprise. However, since scaling up the ship is always possible and something I never shy away from (as you know) I'm happy to give it a go!
Let's see, using the 1,000' vessel as our baseline:
The dorsal width on a 1,000' refit is 5.4m or 17'9" and to fit in the width of the lower Engine Room bays (including outer bulkheads) would require around 24' minimum. That would require a ship length of 1,355'.
If the airlocks were 6' diameter on the original, they'd now be 8'2" (with a 5' drop onto the gangway level with the shuttlebay, so steps would be needed).
Saucer decks (as suggested by the windows) would go from 9'6" to 12'10" and the secondary hull window spacing would go from 12' to 16'3".
This would solve the problem of the Engine Room sticking out of the undercut, since it could now nestle higher up.
The Rec Deck would at last fit into the undercut in its "official" location too.
I think my "central saucer engine room" idea would fit as well - we could have TWO engine rooms in the saucer!!!
* * * * * * *
I wonder how large that would make the pre-refit Enterprise?
Using the "official" length of 947' would scale up to 1,283'
The popular alternative of 1,080' would yield a 1,463' ship
However, if we match the bottom rims of the saucers (my preferred method) then we get a TOS Enterprise of 1,437' - coincidentally a very close visual match for Drexler's cutaway of 1,420'
, so at least we know what it would look like!
In summary - this new refit would be a BIG ship