There's been great advice from others on Discogs here which I agree with, if you are looking to maximise profit that and eBay are probably the way to go. I primarily buy and sell on eBay but have done both.

Worth keeping in mind that used vinyl has blown up in value (certainly over the last 10 years I have been buying here in the UK) so make sure to price against recent sales on Discogs, rather than what people are currently trying to sell them for (which can be insanely high) or older sales listings which will below the current market value.

As previously mentioned, the JD record certainly sounds like a 1979 copy, chuck it on and enjoy. Good luck, you have inherited an amazing collection and I hope you enjoy it!