Thank you for the background information. What you are saying is that my ancestor who said that he was born in Pennsylvania in 1749 could have been born in what today would be Maryland.
Based purely on circumstantial evidence, I would guess that he was born or lived in or near London-Britain township in Chester County. There is a high concentration of other surnames in that township that I associate with him later in Iredell County, North Carolina.
I am planning a trip next winter to check the resources of Chester County. It would seem that I need to allocate the same amount of time to Cecil County. Meanwhile, I will see what kinds of books I can find in my west coast genealogy library that may be helpful.