You say that your ancestor came from Kilraine Co. Donegal. I can’t find a townland with that exact spelling but there is a Kilrean in the parish of Kilteevogue (near Stranorlar) and also Kilrean Upper and Kilrean Lower in Killybegs Lower RC parish, in the west of Donegal.
I searched all 3 in Griffiths but none had a McCue (or variant spelling) listed in 1857. I note there is a graveyard in Kilrean Upper. Always worth a check.
I checked the same townlands in the tithe applotment records for 1834 but again no McCue listed.
You haven’t said what denomination the family were. I’ll assume RC. Kilteevogue does not have any RC baptisms earlier than 1855; Killybegs start in 1850. So you are unlikely to find any baptisms for William, if he wasborn in 1842 and came from either of those parishes.
The William McCue in Griffiths in Barkillew could be related to your William but it’s unlikely to be the man himself as he would only have been 13 at the time. In general, householders in Griffiths would be adults. Where the person was a minor there was usually a trust arrangement, and Griffiths would show that. Barkillew is in Glenties RC parish (Inishkeel civil parish). Their baptism records start in 1866.
Bear in mind that spelling of surnames varied widely in Ireland and the name may also be spelled McHugh etc in Irish records. I checked the 1901 census for Barkillew. No McCue households there then. 75 McCue & 1107 McHugh in the 1901 census of Co. Donegal.
Possibly DNA testing may be a way of matching with others who have additional information about where the family originate. Family Tree DNA reportedly has more people with Ulster roots than any other company. That obviously increases the chances of finding a match. You might want to try them or, if you have already tested, you can transfer your results to them for no fee.
The North of Ireland Family History Society is running an Ulster DNA project and can offer FTDNA testing kits at a reduced price. http://www.nifhs.org (Go to DNA project on the website).