I don’t know all of them either, but I’ll be blunt: They’re all covered in mold because they sat in a basement that had flooded, and into which nobody descended into for a good while, leading the records to sit in soaking covers for a couple of weeks. At minimum.
He should have stored them in HIS home and not his parents’, because he doesn’t have a basement. They do.
We told him it was a bad idea, but no...
As far as value, without the covers they are probably not worth saving.
If you just want to have them to listen to. The warm water, soft toothbrush with a touch of Dawn works for me. I then rinse under lukewarm and pat dry with soft paper towels. You can actually place them in a regular dish drainer to dry.
Try not to get the labels wet. They will tend to crinkle a bit.
I’m more a 45 guy and I do this all the time because a lot of 45’s get stored without covers and end up with a thick layer of dust. They are easier to handle due to the smaller size and the large hole makes them easier to grip as well.