Since the song was done by a Philadelphia group (The Orlons), I kind of doubt that it was about any South Street other than the one in Philly, which is where the Jim's is located, where you can get the best cheesesteak (or pizza steak) in the world.
Also the TLA (Theater of the Living Arts) is located there, where many national acts have performed. I saw wonderful Kenny Rankin there. He played to an enthusiastic crowd of about 500 people, and thanked the audience for sending his kids to college.
South Street is kind of the most youth-oriented drag in the city.
I suppose there were hippies there "back in the day" (I hate that expression).
Ira Einhorn, creator of Earth Day and murderer of a beautiful young woman named Holly Maddux, lived in Powelton Village, which is near Drexel University in West Philly. He was certainly a hippy and an a-hole.
The hippies that the Orlons and the Dovells were singing about in 1963 were probably young hep cats, digging the hottest tunes of the day and learning the latest dance steps. The "hippie" subculture of the "flower children" would emerge on the other side of the country about four years later.