As always, Dennis, your work is outstanding -- I think it serves as a kind of mental putty, filling the gaps between the incomplete ideas in designers' minds in 1978, and what they were thinking at that time.
The thing is, though: If anything characterized the state of the Star Trek franchise in the late '70s, it was uncertainty. One moment they're planning for a new weekly series; another they're considering monthly "movies of the week;" the next they're back to the weekly series; and then doggone it, we're now doing a movie. Let's bring in the guy who did the neon butterfly ad for Levi's Jeans to do the art direction; or hey, I know, let's get the Star Wars guy to do the Enterprise hull stuck on a giant pyramid; nah, on third thought, let's bring back the original guys; or how about, let's get the guy who did Silent Running.
Assuming for the sake of argument -- as your "Copyright 1978" test figures do -- that the Paramount folks were further along with "Phase II" as a TV series, I can't imagine these non-artist supreme executive producers letting this design, as you have masterfully rendered it, pass by unscathed. Of course, there would be some who would make the most unreasonable of requests, like big gun turrets up front, or perhaps some place for "the beaming thingy" that beams people up.
But once the artists emerged from that meeting, I think they'd be tasked with some compromises. The gun-metal deflector dish would go. The purple glow on the nacelles (yes, I know it passed inspection for TMP, but that's cinema) would have been dissed, probably because the U.S.S. Enterprise is an Amuhr-'can ship, dang it (at least that's what "U.S.S." has always stood for, right?), and it wouldn't be glowing no sissy purple color. (Red's an Amuhr-'can color.) And the model makers would probably be asked to attach some new sources of light to make the otherwise drab grey contours more dramatic. This show's in color, I can imagine a Paramount boss saying, so the ship should be in color.
So my suggestion, if you want to take this thought experiment further, would be to make a kind of "Phase II: Phase 2" ship. Imagine how the Paramount bosses would likely have responded to this design, including all the unreasonable suggestions they may have made ("Can we dump the pointy-eared guy already?"), and then come up with a respectable compromise. Think of your ship the way it would probably appear not in the designer's mind, and not in the cinema, but on air. My guess is, the sedate colors and the monotone grey would not make it.
DF "As an Editor, Knows Way Too Much About Unreasonable Suggestions" Scott