My initial decode attempt was incorrect (see "cop motor" post). The partial vin stamp on this motor is 15B, whichmy research indicates "1"- Chevrolet, "5"- 1965, "B"- Baltimore plant. Any disagreement?

Second stamping reads "K1119CMJ. Research I did says "K"- McKinnon plant, "1119"- November 19, "C" - passenger car.......... then I am stumped. My original read was CMJ- police car application 1974. Now I believe that the MJ is the motor option id, not CMJ. However, I cannot find an MJ as a valid motor id. ??????????