Interesting - Your ancestor may be a link in understanding the early evolution of some of these North Carolina styles.
As an aside, not sure if there is any relevance to your ancestors or not, but one of the best friends of Daniel and Squire Boone was a Henry Miller, who was living in Augusta County Virginia when the Boone's migrated southward to the Yadkin, and according to Nathan Boone, Miller worked with Squire Boone Sr. as a blacksmith and gunsmith when the Boones tarried in Viriginia on their way south, working alongside Daniel and Squire Jr. (Daniel's brother). According to Nathan Boone, Miller stayed in Virgnia and had an ironworks operating in Augusta County in 1790.
If I understand correctly, the Narrows your ancestor settled in near were in Rowan County and were near the Trading Ford, and important point along major trade routes across, and migration routes to, Piedmont North Carolina prior to the Revoultion.
There were lots of gunsmiths working in the central and western Piedmont NC region by the time your ancestor arrived. Particularly, at major trade centers, like Salisbury, there were quite a few gunmakers working. Unfortunately, we don't have any signed dated pieces from that period and area that conclusively give you a solid example to look at, but there are a number of examples in Bill Ivey's book that are attributed to the region and general timeframe and these do exhibit some shared features with Pennsylvania pieces of the era. Also, there are many later examples of rifles made in Moore, Randolph, Rowan, Davidson and other nearby counties, that surely evolved from and perhaps incorporate elements that were there earlier.
In addition to places like Salisbury and the Bear Creek area, there was also documented Moravian gunmaking going on in the Wachovia tract, part of which lies in the Yadkin watershed in that period in that timeframe. The problem is that the earliest signed and datable rifles from the area that I know of, which appear to be 1780s, bear little evidence of the earlier Moravian influences, so one wonders how much influence the very early Moravian North Carolina gunmakers actually had on regional styles, or was their work more of a unique style being made contemporary to and in the midst of more prevalent local styles?
Some of the Kennedy rifles in Bill Ivey's book give a good feel for Pennsylvania influences modifed into a unique North Carolina style. Like your ancestor, John Alexander Kennedy left Pennsylvania - a bit later though - during the Revolutionary War - and migrated to North Carolina where he and his sons carried on a prolific gunmaking trade in the Piedmont, a bit east of where your ancestor did. But from what I have read, he initially partnered with a local gunsmith already working in the area and later bought him out. The earliest Kennedy rifles tend to show some influence of his Pennsylvania roots, but also some elements that were perhaps already established in North Carolina when he got there.
So to get back to your original question - I would get a look at Bill Ivey's book or some of Michael Briggs' books and study some of the earliest pieces in there, as well as some of the slightly later confirmed piedmont guns - 1790-ish. And also study the styles of rifles being made in the area where your ancestor hailed from in PA (look at Shumway's RCA Volume 2) and pick a blending of features. Some strong Shroyer-esque similarity would probably not be inappropriate as there is evidence that his work, or at least the style that influenced him, had far-reaching impacts on a lot of gunmakers. Then have fun and blend the styles a bit, but keep toward the earlier elements since your ancestor died in the 1780s, and based on his age probably had a strong sense of style he brought with him from PA - i.e. less likely for an old dog to learn new tricks - but you also have to consider he would have adapted his work to local preferences to some degree.
Good luck
Guy
