PHOTO (UNC Athletics): Hubert Davis. By TOM SHANAHAN The North Carolina basketball head coach succession has been infrequent but consistent for 70 years. The Tar Heels have stayed in the family starting with Frank McGuire (1952-61) to promoting of top assistant Dean Smith (1961-97). Then came the elevation of Smith's top assistant, Bill Guthridge (1997-2000), to hiring former Smith player Matt Doherty (2000-03), although Dohery was as a second choice to former Smith assistant Roy Williams. Ol' Roy…