Griffiths Valuation (taken around 1864 in Co. Armagh) shows George, Hugh, John and Rose McGeown in Derrytagh South. George and Hugh are side by side, tenants of Lord Lurgan. George's land reverts to Daniel McGeown in 1872, suggesting George's death. Rose and John are side by side, with Rose being a tenant of Lord Lurgan and John is a subtenant of Rose (perhaps a son?). Rose's land reverts to John in 1871 and then to Lord Lurgan in 1872.
There is a death for a Rose McGeown, aged 80, in 1869, so she is likely John's mother. This record is not yet available on irishgenealogy.
There is a death for a Hugh McGeown of Derrytagh South aged 72 in 1887, married, informant is an Ellen McGeown, likely his wife
https://civilrecords.irishgenealogy.ie/churchrecords/images/deaths_returns/deaths_1887/06228/4782419.pdfDaniel dies in 1896 aged 55, a widower of Derrytagh South, with Pat McGeown, his son, acting as informant:
https://civilrecords.irishgenealogy.ie/churchrecords/images/deaths_returns/deaths_1896/05894/4672099.pdfI would work through the relationships between these individuals to see what pops up. There are several wills available for McGeown in Derrytagh South on PRONI's website, including one for John (altho' his is not yet imaged, so you will have to request a copy).