It is my understanding Southerners in general were more inclined to trade with England for whatever. Pennsylvania gunmakers were of German origin & were more likely to make or by German styled locks. Hence a GENERAL preference for English style locks if one is building a "Southern" style rifle.
There are a set of 4 paperback books on Southern Long Rifles, by Jerry Noble, of Aledo, Illinois. Range from roughly 10 to 20 years old. You might want to find them somewhere. I like them because, among other reasons, I believe Noble to be honest.
My limited experience, and I guess reading, is that some guys south of the Mason-Dixon line had a different view of what constituted a "Swamped" barrel. There were Southern swamped barrels where the muzzle was larger than the breech. Here is my one and only example.
Bought this rifle because I liked the lines, otherwise knew nothing definite. I have since been told it was Virginian circa 1790, flint converted to percussion. .42 caliber 43-3/8" long barrel, heavily swamped. Muzzle 0.938", narrows to 0.832 about 8" back, then widens at the breech but only to 0.862.
Believe you'd call this an English styled lock