This is one that I have mixed feelings on, to be honest. The whole NWA "invasion" of WWE was a bad angle to begin with. They used a bunch of perpetual mid-carders and jobbers like Jeff Jarrett, Bob Holly, and Billy Gunn to form an NWA stable, even bringing in old NWA title belts. They tried to resurrect old tag teams like The Midnight Express or The Rock and Roll Express (am I detecting a theme?) all of which floundered pretty badly. Then they brought in Dan Severn.
It was actually Bart Gunn...not Billy. They also had Barry Windham turn on Blackjack Bradshaw and join up with the NWA group.
However, I always thought the NWA North American title was just something Cornette dreamed up. Jarrett wasn't the real champion.