As an update to my own question, yesterday I picked up a box of about 3 dozen old radios and not a blessed one would fit the dash. Closest was a '50 Oldsmobile but the knobs are 7" on center instead of 7.5" like the Chevy. Fortunately my dash is already hogged out to accept a 7" on center. Ive ordered the Chevy trim pieces to see if I can make something work.
