"The changes from the series production version and the TMP are drastic to the point of being effectively an entirely new and different vessel. You have to do quite a bit of squinting and fudging to accept it as the same vessel we saw in TOS."
Actually, no. As I pointed out above, the Probert/Taylor work was just a refinement of Jefferies' own Phase II work. And as can be plainly seen by studying the Phase II work, it is an expansion upon the original, not something that starts from scratch. The issue with the TMP ship is it changes the graphics, the font, the finish, the colors... it changes everything on the surface AS WELL as tweaking the shape. When you look at the Phase II design, the graphics and fonts and colors pretty much are consistent with the original so it is easier to see the continuity. But if you look at the shape alone, the TMP and Phase II ships are quite similar. One is definitely a refinement of the other.