The standard amongst the show crowd seems to be rabbit pellets preferably high protein and puritan's pride vit c in the water. Hay or greens is a secondary consideration depending how many you have and how much time you want to spend on them. We use the vit c in the water when we haven't time to pick greens but try to get a grocery bag of alfalfa/clover/dandelions to them every day. It really cuts down on their hay intake. They also get fruit scraps when I make smoothies. Along with corn plants and cattails which are fast to collect but not as appreciated even though they still disappear.
Grass should be ok for him as well. Just curious 
