Hi Bruce,
I would be cautious about assuming that your Morrisons came to the Moville area around 1800 from Scotland, the lack of Eighteenth century records makes proving if they where living in the Moville area in that time period hard to prove. I know that through the Nineteenth century there were many from the Moville area that settled in Glasgow and surrounding districts, there seems to have been a steady stream both ways going back to the early decades of 1800's and possibly earlier.
In a 'The History of the little Town of Moville', by Bishop Montgomery, written, I think in the early 1900's he speaks of his Great Grandfathers Samuel Montgomery's estate at Moville that he came into in 1768, among the nine tenant families he names Morrison, so there were Morrisons in the area in the 1760's, there are also Morrisons recorded in nearby Culdaff in the 1740, Protestant census.
Regards
Joe