My guess is that there is "too little paint" left on that bike for it to be a factory paint job. The paint is gone even in the areas that would be in the shade. It's likely a Deluxe Sting Ray, that was "repainted" with spray cans with Flamboyant Lime paint. While they were at the Schwinn Dealer buying the spray paint, they purchased some "original replacement" decals from the dealer. The Sting Ray decals were available in black for the Lemon-Yellow bikes.
There's a logical Storey behind that bike that has yet to be told.
A closer inspection needs to be done on the chainguard. Is the Schwinn graphics silkscreened, or a water transfer decal?
John