Barry McCain of the Ulster Heritage Group, http://ulsterheritage.com, found mention of MacEoghain in Argyll who were bards and had some connection with the Maguires. Using the Google search term "MacQueen and MacGuire" I found that the names in the title block above are associated with each other. And also with McKown and McQuown, which latter is itself a spelling variant of McCown.
The MacEwens (MacEoghain) were bards to the Campbells of Argyll and Breadalbane and to the MacDougalls of Dunollie.
This does not prove anything about my family history, but is an avenue which must be investigated because it ties together my Irish and Scottish matches and surname with my Maguire DNA. That in itself offers some encouragement.
Barry says that he will look into this more closely when he returns from Ulster in the next couple of weeks. It also give a bit of credibility to our word of mouth family tales of being of highland Scots descent. In this case the Scots most likely having come from Ireland.