I did find also this in the PRONI will calendar, I'm not quite sure how to interpret this but again, if it's the right man, it appears his estate did go to an Edward Rooney, which squares with the information given by the OP.
Rooney James Edward of 16 Park Street Lurgan county Armagh labourer died 1 October 1958 Administration Belfast 29 October to Edward Rooney labourer. Effects £348.
Not quite correct- the PRONI entry says that Edward Rooney, labourer, was granted
administration of the estate of James Edward Rooney. It appears that JER did not leave a Will, or at least a valid Will, and Edward Rooney applied and was granted the power to administer JER's estate according to law. This does NOT mean that his estate went to Edward Rooney.
Added- from PRONI deaths- (born c1885)
D/1958/172/1021/67/172 James Rooney 1st October 1958 73 Male Lurgan