Complex sentence: Originally it was the first full-time FM Atlanta classical music station, with the call letters WGKA-FM, it changed to WZGC in 1972, when it began as an oldies station.
Split into simpler sentences: Originally it was the first full-time FM Atlanta classical music station, with the call letters WGKA-FM. It changed to WZGC in 1972, when it began as an oldies station.