Have you checked out these? There are two Certificates here - one is the birth of Michael Donnelly in 1870 and the other is his parents Marriage in 1866. Both are free to download and worth checking out - Gortnagoona is just 5 miles outside Roscrea, while Clonmore is a village about 9 miles from Roscrea and 4/5 miles from Gornagoona. If I find out any other info I'll post it here.
The links are:
Michael Donnelly & Sarah Ryan Marriage 8th February 1866
Michael Donnelly Birth 4th February 1870
Dick. Roscrea Volunteer with Ireland Reaching Out.