Regarding 1940s and 50s grunge: I want to strongly agree with Dave Evans. To put it another way:
We have no better reference of color in the 1940s than Delano and never will.
Moreover those color renditions are fully plausible: one does not see gross miscoloring.
Finally, if your audience has seen the Delano photos, then weathering to that level seems to me to exactly fit the bill. Everything we do is staging, not reality. When you watch a play, you’re not fooled into thinking it’s real, but if it’s good it *feels* real and the staging supports that. Isn’t that what we’re trying to do?
