Heat oven to 450 degrees F.
Prepare the stuffing mix according to package instructions in a bowl.
Place roast, fat side up, on a clean surface. With a sharp knife, cut along length of pork loin without cutting all the way through. Open up pork like a book. Spoon stuffing down center of pork. Close pork over stuffing. Tie up loin with kitchen twine, spacing twine about every 1 1/2 inches. Rub pork with 1 tablespoon olive oil. Stir together the flour, salt and pepper in a small bowl. Rub the seasoned flour mixture evenly over the pork loin.
Toss together sweet potato chunks and the remaining 2 tablespoons olive oil in a roasting pan; spread out evenly over bottom of pan. Place the tied pork loin, fat side up, on top of the potatoes in the roasting pan.
Roast in 450 degrees F oven for about 10 minutes. Reduce oven temperature to 350 degrees F. Continue to roast for 55 to 60 minutes or until instant-read meat thermometer inserted into the pork, but not in the stuffing, registers 150 to 155 degrees F and potatoes are fork tender. Let the pork rest for about 15 minutes; temperature of pork should increase to 160 degrees F. Keep the sweet potatoes warm. Remove the twine from the pork loin before slicing. Serve with potatoes.