Bill Lawson's book, "A Register of Emigrant Families from the Western Isles of Scotland to Ontario, Canada", has the following family:
John McLeod 1810-93 (son of Donald) Upper Carloway, Lewis
married to Marion Morrison 1813-1899 (daughter of Donald)
1. Donald 1833- m. Catherine MacLeod (her family is also in the book)
2. Duncan 1838-1917 m. Margaret MacDonald
3. John 1841-died in infancy
4. Malcolm 1842-1913 married Ann MacIver
5. Angus 1849-1924 married Mary MacGregor (family also in book)
7. Mary Ann 1852-1959 married John Robertson
"John MacLeod and family emigrated from Carloway in 1851 and settled in Huron Township, Bruce County."
You should be able to find these family members on the 1851 to 1911 Canadian census, if they stayed in Canada. You may also find your family on the 1851 Census of Scotland.
I also had family on the 1851 emigration from the Isle of Lewis--Murrays and MacDonalds, amongst others--settled in Ripley Village, Huron Township, Bruce County, Ontario. My 'Morrisons' settled in the Eastern Townships of Quebec.
You are correct that these people sailed from Stornoway Harbour. They were given free passage on two of Sir James Matheson's trading ships which were taking 'pig iron' to North America--for the railroad, I suppose.
There is a lot of information on this emigration and you can email me directly at firstname.lastname@example.org
This looks like your family and I hope that it is. Bill Lawson on Isle of Harris can help you with your genealogy. You will find his website online.