ATLANTA — High wire walker Nik Wallenda has a date in mind for crossing a nearly 1,000-foot-deep gorge in the northeast Georgia mountains, 45 years after his great-grandfather accomplished the feat. He intends to walk across Tallulah Gorge on or very near July 18, 2015, his agent, Winston Simone, said Friday. That will be the 45th anniversary of the day Karl Wallenda successfully crossed it as an estimated 30,000 spectators watched.