From what little I know about using ginger, that should be 2.5oz. Papazian says you should use fresh, grated ginger. He says 1oz will add considerable character, but that he's used as much a 4oz in a batch.
May you go marching in three-measure time
Dressed up as asses, drunk to the nines
Swing from the rafters, shouting those songs
Gone unsung for far too long