Wow, fine work! Having to rebuild the interior walls must have been a pain but obviously worth it in the end.
I've thought about similar projects but all of my E series engines are too small in the cab area to allow any margin for measuring mistakes, which I invariably make. Plus most 3 rail diesels, especially from 3rd Rail, have a lot of lighting wiring stuffed around the cab interior assembly. If I did try something like this, I'd be strongly tempted to illuminate the gauge faces just for the fun of it.
Thanks for posting this and the rest of your series.