First, you should tell or describe the file name of any "file signatures from keys" backup that you have.
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I simply numbered them.. Not looking at a file and thinking it's BTC trying to recover it, trying to recover keys I know were once on this drive.
Based from the context, those are recovered bits from a disk image or similar?
AFAIK, there are ways to identify bitcoin private keys that are once in a wallet.dat file.
It's what recovery tools like Pywallet has been utilizing to check for potential deleted wallet.dat files and private keys from a drive.
If you want to give that a try, use pywallet's --recovery command:
https://github.com/jackjack-jj/pywallet