Place bread in a bowl; pour milk over it. In another bowl, mix veal and pork. Add onion, garlic, zest, and parsley. Add salt and pepper. Mash bread mixture to form paste; add to meat mixture. Mix; add egg. Combine well. Cover with plastic wrap; chill 1 hour.
Heat oven to 350 degrees. Form mixture into twelve to sixteen 1 1/2-inch balls. Heat 1/2 tablespoon oil in a skillet over medium heat. Saute half the meatballs until brown, a few minutes on each side. Transfer to a pan big enough to hold all the meatballs. Repeat with remaining oil and meatballs. Place in oven to finish cooking, about 20 minutes.
Cook rigatoni according to package directions. Toss meatballs in tomato sauce; serve with grated Parmesan over rigatoni.