Game King 6.4 and Game King 8.2 are totally different animals...
6.4 is emulated and requires a GE011 game installer and an AE011 os installer. The AE011 version depends on what bootchips you have and what brainbox and needs another program if you have dynamic buttons. If you have never messed with the AVP Emulated games I would read up on them. Honestly, if you were making a dedicated Game King machine there is nothing wrong with the emulated version, you just can't load any family 014 games with it (GI014 or AI014). JUST MAKE SURE TO SET THE RTC/DATE AND TIME or you will get a game unlicensed red screen error after 10ish mins.
I had a bunch of GK 6.2's on G20's (001176 I believe) and kept them that way because 8.2 was horrible to install when it first came out.
The likely reason you can't find much about 8.2 is because it didn't last long and was considered "8.2" as a combined game program set. It was literally 18 individual game loaders along with 2 feature packages so it was quite time consuming to install. The actual primary Poker set was called AVP Poker 1.1. I dont know if IGT ever combined it all into a GI or PI package or if they just went on to 8.3. I know I had 4 of them and eventually upgraded them to 2 8.3's 1 All Star and 1 Ultimate X.
You would install the OS, game menu feature, ez setup feature and AVP Poker 1.1 and then add the keno, blackjack and slot games individually. The AVP Poker 1.1 was required but I don't think you had to install all the others if you didn't want them, I did because I had them at the time. I know IGT combined all 18 games on 1 license but that doesn't mean they all have to be active.
Attached is a screenshot of the programs I had installed when "8.2" first came out.