Hi, Lori. The Mathis/Matthews surname variation is certainly within the realm of common perturbations at the time. You didn't mention what the genetic distance (GD) is to your 67-marker yDNA Mathews match. The testing company should give you that information but, alas, unless you can obtain the other tester's actual STR results you're pretty much at the mercy of the testing company's inference. Point being that some markers are known to mutate quicker than others, so one person's match of GD 2 may not be equal to another match of GD 2.
That said, if your reasonable point of confirmation is around 1800-ish, at 67 markers I'd definitely chase matches from 0 to 1 GD; 2 if you have time; 3 and 4 as maybes, but that would be stretching any ability to corroborate paper-trails with the matching researcher. FTDNA broadly states, for example, that at 67 markers a GD of 0 is predicted to have an MRCA 50% of the time within three generations, 90% of the time within five generations.
If you haven't already done so, the next step is to reach out to the Mathews match--assuming it's a relatively solid one--and open a line of communication. You need to start comparing notes and, probably, using collateral information like that land purchase and other location indicators within specific timeframes, plus identification and movements of any allied families. A wonderful thing about the endogamy that resulted from the close-community, agrarian expansion in the U.S. for a number of generations: clusters of surnames often moved together.
A personal preference tip; discard at will. :-) That first email to a DNA match is similar to a first impression when meeting someone: you have a brief period to motivate the other person to write back. Be charming as you introduce yourself; give a brief Burke's Pentad (who, what, why, when, where) about the possible connection; include a statement about your willingness to share information; and close with a call to action, a request that they write you back; if you feel comfortable doing so, include additional contact info, like a phone number, to show you're open and sincere.
I try to make it a habit to always reply to any DNA match inquiry, but I'm more likely to want to engage if that incoming email is something better than, "Looks like we may be a DNA match. Write me."
If you have another close match in additional to the one Mathews, putting your heads together on the problem collectively not only increases chances for success, but it's fun. Good luck!
