Hi. Sorry for delay; I've only just seen your post. Can't really help with your question, but a few pointers, in case you want to research forensically:
The village mentioned in the 'Gwynne' posts is actually St Dogmaels (or Llandudoch in Welsh), just across the river from Cardigan on the S.W. Wales coast. There appear to be many variations on the Gwyn/Gwynn/Gwynne/Gwinn, etc surname. Gwyn in Welsh is 'Fair' or 'White'. The Gwinn version may be an Anglecised version of the basic 'Gwyn'. The St Dogmaels/Cardigan area has a rich seafaring history, and my father could recall at least 10 sea Captains living in the village when he was a boy (late1920s).My Grandmother (b.1899) had a great interest in the Patagonia migration from Wales (Mimosa, c1865 etc), but I can't help with 1755 era.