TractorData.com John Deere 272 tractor information
Four posts in this thread and you still have not told us how large your field is.
Roto-Tillers and Disc Harrows are two forms of soil mixing tillers. Your Deere 2720 is only heavy/powerful enough to pull and Disc Harrow with 18" diameter pans, the MINIMUM weight of Disc Harrow which is effective. Skip the Disc Harrow; the PTO powered roto-tiller will work better.
Smoothing seems to be your primary objective. After roto-tilling the soil will be loose. As recommended by JENKINSPH a Land Plane or Spike Tooth Harrow would work. I have a Ratchet Rake FEL bucket attachment which will work too, perhaps a somewhat more aggressive grader. I also have an ETA Landscape Rake with gauge wheels, which is also good for finish grading when used on an angle. Landscape Rake is less aggressive than the Ratchet Rake, about equal in aggressiveness to a 1/2" chain harrow.
A Cultipacker is good for rolling in seeds but is is not great for grading type smoothing, as I interpret your need.
As you have a Box Blade, why not use it? Box Blades take quite a while to learn to use well but it should suffice for your need. You will not get the field perfectly smooth with a Box Blade but you can succeed the Box Blade with a Spike Tooth Harrow, Chain Harrow, Ratchet Rake or Landscape Rake with gauge wheels.
You can buy a Ratchet Rake from the T-B-N store, button at top of this page.