In a large bowl, mix the pork, chuck or lean ground beef, veal, provolone, ricotta, parmesan, pecorino Romano, breadcrumbs, lightly beaten eggs, salt, pepper, and garlic. Mix loosely but mix well, making sure you do not "pack" the meat.
Roughly divide the mixture in half, then each half in half, and lastly each quarter into halves so you have 8 portions. Form into balls that are about 2 1/2-inches to 3-inches in diameter.
If NOT using oil from a tomato confit, add a little fresh olive oil to a large skillet. If using a confit, spoon most of the oil and about half the tomatoes into the skillet, crushing the tomatoes with the back of a spoon gently. Add three or four fresh rosemary branches to the oil you are using. Heat over medium-high. Reduce slightly if the oil begins to pop.
Once the oil is shimmering, and working in batches, add the meatballs. Cook, turning until well browned on all sides, about 10 minutes. The meatballs will NOT be cooked through. Use a slotted spoon to remove each meatball to the pot of sauce and repeat the searing process with the remaining olive oil and remaining meatballs.
Once all the meatballs have been transferred to the sauce, add the remaining fresh basil leaves to the sauce and simmer all over medium-low heat until the meatballs are cooked through, about 1 hour. NOTE: if using a tomato confit, use a pastry brush to apply a thin amount of the flavored oil to toasted baguette or a homemade garlic bread if you like, and add whatever remains of the confit tomatoes directly into the sauce for added flavor.