As per Bill, it can't be stamped until it's cast, so your date cypher is wrong. The Serno is F= Flint MI plant, stamped July 12, one day after casting. The LB is listed in 1957 as truck series 31-32-36-3800-4000.
The 230 is shown as STD, 292 and 283 are shown as optional in K series. If it was cast in mid year 1962 maybe they did use left over. I think I'm going to have to doubt that. What does the VIN tell you about what year your truck really is? Should start 3K...
