Templemore is in Tipperary North Riding. The RC parish records are on line from 1815-1877 for baptisms and 1827-1894 for marriages.
These records are available for a fee from a not for profit History Foundation.
You have both parents names which is an advantage as you can search for all the children's (siblings)names as a group for less than an individual search x how ever many siblings. Sort of a package. Most Irish genealogy is not free and also usually spotty with gaps.
Griffith Valuation is used now as a census substitute for 1850 Tipperary. www.askaboutireland.ie
Look for those in either Thurles or Roscrea Poor Law Unions.
There are 7 John Ryan's living in the Parish of Templemore.You will be able to count the number of houses to determine how many there really were, often people would occupy/rent/lease several parcels of land to make farming
I wasn't able to find the spelly O'Shannesy so tried
O'Shaunessy but came up with no record for the Parish
The spelling was present in Ireland as the 1841 UK Census which identifies Irish born person's shows 4 people with that spelling.
Also a Marriage license in 1832 in the Grant Book for Dublin also show a Francis O'Shanessy and spouse to be
Many programs are spelling specific rather than being
forgiving on spellings which is necessary in Ireland.
The 1901 Census shows 2 spellings the same, one from Clare and 1 from Limerick. www.census.nationalarchives.ie
the are the only ones in Ireland by 1901.www.genealogy.nationalarchives.ie
gives the Tithe Applotments for 1820-1839. You might find something there.
There are 62 Ryan's in Parish Templemore.www.familysearch.org
was look for a death of Rose Ryan, there are many but too young these are just examples
you will need to search further.
Rose Ryan born 1837 died July-Sept 1917 (too early for an 1830 birth.
Irish Prison Records
1849:Rose Ryan born 1799 age 50 Clonmel, Tipperary for stealing turnips
18551: Rose Ryan born 1799 age 52 Clonmel, Tipperary for
The Irish telephone book shows 1000 Ryan's living in Tipperary but this includes those with a first name Ryan or a name beginning with R. There are Ryan's living in Thurles
and Roscrea and Clonmel. I think letter writing is out because of numbers as well as not knowing the actual location. (couldn't look up OShannesy as the telephone book is spelling specific)