That's why you need the land entry record.That gives the 1816 date and the "of Clay Co KY" description, and the land description.
The patent gives the exact same land description, which shows that the land entry recorded for James Pace "of Clay Co KY" in 1816, was subsequently assigned by him to Burtner.
The land entries are published in "Indiana Land Entries. Volume 2, Part 1: Vincennes District, 1807-1877", Margaret R. Waters, ISBN: 9780806317373.See the Genealogical Publishing site for details, but you may be able to find it in a genealogical library.
If you do consult this book, look for another land entry by a James Pace, in Lawrence County in 1820. This would probably be your wife's ancestor, as mentioned in the history of Shawswick Township given at http://www.ingenweb.org/inlawrence/shawshis.htmhttp://www.ingenweb.org/inlawrence/shawshis.htm.See where it says James Pace had a land entry in 1820 in Shawswick Township?If you can find that 1820 land entry, you can then compare it to the land described in your wife's ancestor's estate papers.