In our yeast guide, we mention that for ales above 1.050 gravity to pitch 2 packets of yeast. For lager strains, we recommend 4 packets if the gravity reading is above 1.050. Based on a 23L fermenter volume
If you are brewing a hybrid brew, we would suggest to follow the lager instructions and use 4 packets of yeast.
The M54 California Lager is a great yeast, as this is a hybrid yeast.