In your largest mixing bowl, combine the sourdough, livers, ground beef, celery, onion, parsley, eggs, raisins, Parmesan and nuts, tossing gently with your hands to combine. Whisk the rosemary, oregano, thyme, bay leaves, poultry seasoning, salt and pepper together in a bowl, scatter over the stuffing and toss again with your hands. Taste and adjust for salt. Refrigerate, covered, until ready to use as a stuffing or to bake separately as dressing. To serve as a dressing, pile about two quarts of the mixture into a 9-inch square baking dish and bake at 350 degrees until the top is evenly browned, about 1 hour.