I can advance $150 USD to whoever wants to make this program and post it on Github as opensource. You must already have a reputable repository with something of value listed in it.
You can private message me for more info if you are interested.
Did you see the post above from LoyceV?
It looks like such a tool already exists.
It appears that usage in linux would likely be:
cat FILENAME_OF_YOUR_FILE_FULL_OF_HEX_KEYS_HERE | bitcoin-tool --input-type private key --input-format hex --output-type --private-key-wif --output-format base58check --input-file - --batch --network bitcoin
I tried this command and about 10 other variations; nothing happens.