pp, you've shined the light on an aspect of cinema that usually doesn't get much airplay. We've touched on the topic occasionally, but not to the depth you have. Bravo!
After many viewings of GF and II, I found myself scanning the background for decorations, knick-knacks, furniture, etc....but not so much the clothing. The obvious costumes were always interesting. Some are subtle and some rather garish, like that huge necklace Kay is wearing when Michael smacks her in GFII. It looks like something from Star Trek.
A few years ago I posted an observation about Luca's squeaky shoes as he walks down the hall to his demise in Bruno's bar. At the time, Professor Turnbull commented that during the war cheap shoes squeaked. I only mention this as another avenue for you to explore. There are some clothing items that we don't even see that are made for the times.
I also thought Luca's hat was a little large in the brim. Looked like it could have been a cowboy hat for city slickers.
Great job.