What you're doing is really interesting!
Based on the round tail light and the configuration of the bumper, I don't think it's a Chevy at all. The 1929 and 1930 Chevys had a race track shaped tail light and the 1931 and later had an oval shaped tail light. The rear bumpers were mostly "bumperettes" -- short bumpers, one on each side. I'm attaching a couple of photos.
On your next dive, if you could get to the front of the car and get a close-up of the top front of the radiator, every car of that era had an emblem there, usually with the make of the car.
You also may want to post your post here:
https://forums.aaca.org/forum/66-what-is-it/ It's the AACA forum for identifying old cars and their parts. Since it's probably not a Chevy, they will likely be able to tell you what it IS.
Good luck with your research. Please do keep us posted.
All the Best, Chip