Well, this has been interesting and educational, with the info from 6bbl.
I hope the cars others referred to as examples were/are original & untouched.
Forgive my skepticism, but in the 50+ years I've been around these cars I've yet to see a '69 non-RR orange 383/335 myself; obviously they're rare.
The 925/926 info is pretty clear, and in that sense better info than the tags from other plants.
What I HAVE seen, like many of you, is modifications, repainted engines, and a lot of creative disinformation...
Or worse, the folks that attempt to legitimize a car that isn't a correct restoration.
I agree the '70s are a somewhat different deal altogether.