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Just to clarify, the townland would be Doonsallagh East in Kilmurry (Ibrickan) civil parish. This parish is just to the south of Kilfarboy parish. Here is the 1855 Griffiths Valuation head of household listing for Kilmurry (Ibrickan) parish and you can see Denis in Doonsallagh East.
I don't think the marriage record is available. I located two possible civil death index records for Denis.
First name(s)DenisLast nameM'NamaraAge at death77Birth year1809Registered year1886Registered quarter/yearJul - Sep 1886Registration districtKilrushVolume4Page185
First name(s)DenisLast nameM'NamaraAge at death84Birth year1805Registered year1889Registered quarter/yearJan - Mar 1889Registration districtKilrushVolume4Page237