Too much calcium has been shown to cause bone/growth problems.
The only grain-free large breed puppy food I would feed is the Orijen Large Breed puppy. This is what we are feeding our large breed pup.
^^this^^ orijen (and maybe acana grainless) are the only grainless foods that i know have a maximum Ca level of 1.7%, which is as high as id want to go on a large breed pup. most all the other grainless foods(including TOTW and Instinct) are around 2% and up. i can tell you on the GSD forum i am on, the only grainless food that gets any consideration for a gsd pup is orijen. the rest are better left for adulthood, imo.
otherwise the choices for a large breed pup are any large breed puppy formulas which will have the lower Ca levels (examples) Blue buffalo large breed puppy, innova large breed puppy, wellness super 5 large breed puppy, solid gold wolf cub...or any adult food that has around 1.5% maximum Ca levels.