I don't remember the effects of FF8 and the 8 bit pallet.
But with FF7, the TNT patch is really an 8 bit pallet bypass patch. Just use that patch, check the Nvidia TNT box...and you should see something happen. Unless you get a layering problem. My PCI-E 6600GT shows FF7PC, alright, though.
Don't know what it does with FF8PC....haven't bothered with it...the video card, I mean....not the TNT patch...