You really should not use a "K" engine for this date calculation, they sat for a while because there was not a high demand. Mine was cast on August 11, 65 before 66 production began, assembled on August 23, 65 at the Cleveland plant, shipped to San Jose (about 7 to 10 days by rail) where it sat until the scheduled assembly date of October 18, 65, a total of 68 days, 9 1/2 weeks. I would guess that an "A" or "C" code engine would be a week from cast to assembly, a day to assemble and move to the train, a week to ship (Ohio to New Jersey) and a couple of days getting moved around at the final assembly plant, say 16 days. Mustangs were hot and Ford was in the sell, sell, sell mode.
Jim