Hi Rich,
Very interesting gun but I am skeptical that it is an export fowler from England. It uses English parts but in a composite way more like something made in NE. For example, I believe the side plate is from a pattern 1756/1777 British sea service pistol. The engraving on the guard is very New Englandish, the lock is almost certainly a replacement. The wrist escutcheon is very familiar and I think it was used on Ketland and other export guns. It would be interesting to determine the stock wood.
dave