Re: Address
If the land is registered with the NI Land Registry, then you can find out the current owner by contacting them. (There is a search fee to pay). If it’s unregistered land then current ownership information may not be in the public domain.
Street names and house numbers were only introduced in rural areas in Ireland in the 1950s. Prior to that the townland was sufficient to identify a person. So you won’t find 300 Gorticashel Rd in any old records because that address didn’t exist then.
Griffiths Valuation listed all the tenants for each property with land. If you know where the house is, and can identify it on Griffiths maps, then that may help identify previous tenants. (Most land was rented rather than owned until the early 1900s). After the initial or primary valuation, there were subsequent revaluations which noted changes of tenants/owners. The revaluation records are in PRONI, Belfast. They are not on-line anywhere.