It looks like a nice custom bike. More pics would help get the date. Is the number on the BB or the dropout? If it's on the bottom bracket then it could be a 46 or 52, on the dropout could be a 53, 56, or 57. The type of fork crown on your springer indicates an older model. I believe Schwinn changed from the style you have to the newer version in 1955. The crown is different on the newer model. Yours is facing backward and should be turned the opposite direction, if I see the pic correctly.
It was made in Nov of 68. In 1968 there were three Schwinn models like that. It could be one of two 20" models, Typhoon or Skipper. Same bike except the Skipper came with training wheels. Maybe they were taken off.
The Fleet had tabs for a tank.