I've owned a few Gibson from the mid to late 70s with twisted necks. It's something I watch for now. As to any "fix", I've not heard of anything that works. I've heard tall tales. I don't believe any of them.
I would not buy any guitar with a twisted neck, period. Having said that, I have a 1998 Seagull that looks like it went through the war and it has a twisted neck. It is obvious. However it still plays fine. I have another S6 neck waiting in the wings if it ever "fails".
If you like the guitar, you might overlook the flaw, as long as it plays okay.
If not, bail. Even if you lose money. Bail and take the loss, otherwise it will eat your brain.