Note that in Ireland the name McKeever can also be spelled McIvor or McIver. And you will see other variations.
Researching in the early 1800s can be difficult due to the general lack of records. It is long before the start of statutory birth & death registration (1864) and you need to rely on church records, where they exist. So you need to know the precise denomination of the families you are researching.
Looking at the 1831 census of Co Derry, there were 4 McKeever households in Kilcronaghan. 3 lived in the townland of Brackagh Rowley (which has disappeared by 1859 but which might now be Brackaghlislea). Pat, Richard & Michael. And one lived in Gortahurk (James). All were Catholic.
As far as church records go, Kilcronaghan Church of Ireland (ie Episcopalian) have records from 1790 onwards, Tobermore Presbyterian from 1860 and Catholic from 1848. The Church of Ireland kept burial records, the other denominations did not.
The tithe applotment records list farmers in the parish around 1828/29. (Servants, labourers and others without land were not normally listed.). The tithes show a John McKiever in Gortahurk in 1828 and again in 1829. He’s not in the 1831 census so that could be because he had died, which fits with your information that your John died in 1830.
http://www.irishgenealogyhub.com/derry/tithe-applotments/kilcronaghan-parish.php
You will see some McIver/Ivor farms too in Gortahurk. One of them will likely be the James McKeever in the 1831 census.
The next set of major records we use in Ireland is Griffiths Valuation. 1859 for Gortahurk. There were no McKeevers (or variants) listed in Gortahurk in 1859.
2 McKeevers in Brackaghlislea in 1859.
156 McKeevers in the 1901 census of Co Derry. All were Catholic. None in the townlands mentioned in the 1831 census.
About 100 Wallace households in Co Derry in the 1831 census. None in Kilcronaghan parish. Wallace is mostly a Presbyterian surname (judging by the denominations given in the census). Presbyterianism + a Scottish name + Co Derry points to the family probably being of Scottish descent. They likely came to Ireland in the 1600s. (Some 200,000 Scots settled in Ireland at that time).
