Nice LC!!
Try soaking in extra virgin olive oil for awhile, then with a wooden toothpick, etch away any softened crust.
Clean with a some TSP or a mild soap, rinse, dry, then apply some paraffin wax and buff with a soft cloth.
This method works for me. There are so many variations of cleaning.
Good Luck
Here is a before and after 52 LC I found a month ago it was pretty nasty I used a tiny bit of naval jelly diluted in water and brushed it with a toothbrush. I figured the ground action killed any numismatic value to the coin might as well make it look better. And it did! Better than I expected.
Thanks for the feedback everyone. I'm still working on cleaning it up. In a week or so I'm going to hit this spot again. From what I've read the area was mill based small town in the late 1700's on up. It has to be a spot with more to offer!!