I was looking for something in my files and came across a 1976 issue of Star Trektennial News
(written and edited by Susan Sackett) that has an interview of Matt Jefferies in it. I thought the below portion of the interview is coincidentally relevant to this thread. FYI.
"WHAT DO YOU THINK ABOUT FRANZ JOSEPH'S BLUEPRINTS OF THE ENTERPRISE?
The set of Blueprints that I saw two years ago...he's a marvelous draftsman. He did a hell of a job of drafting, and that's what the heck it is. He took what we had and added to it based on what we had...he merely expanded...he invented like mad. As much as I hate to admit it, I got thoroughly peeved over the whole thing, because he did take the design work that somebody else had done and built on it. We're talking about another generation of fans, and they pick this thing up and all of a sudden it says STAR TREK and it's gospel. And it isn't, because what didn't actually come out of what we did is a pure fabrication that's happened since then. I got narrow-minded and thoroughly peeved over the fact that there was no mention of what he used as a base to build upon."