Nazgul, my car (1826) has them too. I don't see a lot of rust around them, but haven't stripped the undercoating in the wheel wells either, so there may be. If you're doing a full restoration, might as well weld them up. I'm sure they were done with rivets as an easy fix when Ford sent teams around to do the updates and fixes, and welding would have required too much extra work (re-lining the front trunk, scraping undercoat etc.)
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