Was your bike originally equipped with a Torpedo headlight?
Note: the Model K19 Deluxe Hornet was the 1958 Model as seen on the 1958 Fair Trade Prices page and on page 9 of the 1958 Schwinn Dealer Catalog. The Model K15 Hornet was also the 1958 Model as seen on the Fair Trade Prices page and on page 15 of the Schwinn Dealer catalog, but it was equipped with the Torpedo headlight.
Since your bike has a serial number that was found on 1955 and 1957 Schwinn bikes, the 1955 possibility is eliminated because both the Deluxe Hornet and the Hornet of that year were built on the "Schwinn double bar frame." Your bike is built on the cantilever frame and is thus the 1957 edition. The 1957 Schwinn Deluxe Hornet was equipped with a Delta Rocket Ray headlight. If your bike was originally equipped with a Torpedo headlight, it would follow that it was a Model F15 Schwinn Hornet rather than a Model F19 Schwinn Deluxe Hornet.