I will go with the 1960 date on the Schwinn Continental. I have one in beautiful condition and it is the first year derailleur Continental. They only had these for two years 60-61. They came with the Tour de France Simplex rear derailleur and front suicide shifters. I also have the first year Varsity by Schwinn the lower end heavier model. The Continental of that year came with Ideals saddle, alloy stem and bars and a real nice decal set, like a coat of arms. I can give more details if you like. Here is a poor photo of it on Old Roads that I put up some years ago with a older camera. I should update the photos. Anyway the GO serial designation you gave is really G ZERO as they did not use the two alpha designatioin at Schwinn till 1965.
Photo link...
http://www.oldroads.com/
Ray Homiski
Elizabeth, NJ