Been awhile lol,
Take the tines off the box blade, the key is to use the top link to adjust the box blade for the correct cutting edge pitch. Most will have two cutting edges, one toward the inside of the box facing forward and one trailing edge facing back. Adjust the tilt until the blade on the front facing forward is just slightly above the ground, talking like 1/4in or there abouts. You want the rear blade to do the smoothing. So when it's set up correctly, the front facing cutting edge shaves the high spots and the rear cutting edge smooths and fills the low. Be careful of pushing with the box blade in that position because it will gouge the ground when going in reverse, not to mention it will put a great deal more stresses on the 3-point as it's designed for pulling not as a dozer.
BigRed