Couple more suggestions: John McLennan (by the Lake) - the papers are at the National Archive. There are several pages on him in the book "A History of Glengarry" by Royce MacGillivray & Ewan Ross. Also, a book by Robert Fraser "As Others See Us", reproduced by Alex W. Fraser has info on this family.

Regards,

Evelyn Goulet, Castle Tioram
Finlaggan Councillor
Clan Donald Internationa,
Host, Glengarry Genweb