In a large sauce pot (8-quart size minimum), heat 1/4 cup of the olive oil on a very low flame. Add the diced onion and cook slowly until it has turned translucent. Do not brown the onion, but allow it to almost melt away. Add the garlic cloves and very lightly cook them in the oil until golden before adding the tomatoes and all their juices. Add salt and pepper to taste, and the basil leaves and set the heat on low. Allow the tomatoes to cook at very low heat for at least 2 hours before adding the meat.
Make the meatballs: mix the ground beef and veal together in a large bowl. Combine the bread and milk and mash together to form a paste; add the bread to the ground meat. Add the eggs, garlic, parsley, cheese, salt, and pepper to the meat mixture and combine all the ingredients using your fingers to mix uniformly, but do not over mix or the meat will dry out when cooked. Pick up 2 tablespoons of the mixture and roll it into a ball shape, between the palms of your hands. Do this until you have used all the meat. This should yield approximately 24 meatballs.
Place the remaining olive oil in a heavy skillet and heat over medium flame. Add the meatballs in 1 layer and brown on all sides before removing. Do this to the remaining meatballs until all are browned to a caramelized color. After all the meatballs have been browned and removed from the skillet, add the sausage links and brown well, following the same method as the meatballs. When all the meat has cooked, add to the tomato ragu, which has been cooking for 2 hours and cook an additional hour. Serve the tomato ragu over rigatoni pasta cooked to manufacturer's directions. Serve the meats on another plate as a second course.