FWIW.... Excess ZDDP has been reported in some research to cause different problems. (Spalling on some wear surfaces). IIRC the test showed such issues starting at around 2500 ppm. 1200-1300 ppm is adequate, and is the typical range of the older oils.
My machinist warned me about that. He said you can have to much zinc. He said for running the Lucas classic oil would be fine but he recommended that i not use it and the zinc additives together.