Success! I got a lead from someone who lives in the general area of Kanturk/Newmarket to look at townlands near Tullylease, not too far from the aforementioned towns. The townland of Knockavulling there is variously known as Knockavullen, Knockawillin and Knockawillen, depending on the source. Anyway, I found Knockawillin in both the 1901 and 1911 census returns and found the people for whom I was looking and all the details matched, so I know I found the right area. I guess one of the difficulties in this kind of research will always be the variations in spelling, depending on who wrote down the information and how good an ear they had for Irish place names. I managed to find so much information just by that one lead, and have now identified my great-great-grandparents and great-great-great grandparents and numerous members of their families.
Ceallachain