I definitely think many of the details in these diagrams reflect the original concept MJ preferred, such as a bevel around the lower edge of the saucer, the more curvaceous underbelly of the secondary hull, the "reversed" windows on the pylons etc. etc.
But then there are many details that reflect changes made to the model after they were built, such as the smaller bridge dome and deflector dish, mods. to the nacelle end caps etc. etc. So it's a mixed bag when it comes to these diagrams. At best they can only point us in the direction of what an original build “E” might have looked like?
Plus, I don't think they help much as far as rationalizing the (in universe) scale overall, since the changes are pretty small compared with the later TMP refit. You'd be better off just ignoring the scale in these diagrams and using whatever scale you think works best?