Because Cleveland Welding serial numbers repeat and because people often either leave off the serial number suffix or misread the Cw symbol I’m generally uncomfortable predicting the date from just a serial number without at least photos of the bike or better yet pictures of the bike and the serial number.
What it sounds like is a 1957 bike when they dropped the Cw and replaced it for the year with the letter G. It appears the change reflected AMF discontinuing bicycle production at the old Cleveland Welding plant and moving it to Little Rock Arkansas.