The image you posted (from page 95) is of a shuttle that is significately smaller that the shuttle from the movie.
The blueprints show the same as Mr. Scott's Guide, for the docking ring. Which looks different than the production image (naturally). The doors seem to be the only other thing different.
EDIT: Every blueprint I can find shows the same scale as Mr. Scott's Guide.
Bigger pic of the blueprint above.
I also found this:
It's got a writeup about the shuttle and Andrew Probert's matte paintings showing it in the shuttlebay. They say it's smaller (speculation of the website owner?) but it looks the same to me.
Re-looking at your production photo, I think the docking port just looks smaller because of the angle. If you saw it full side-on, it would probably be the same size.