Brian:
Welcome to Ireland Reaching Out!
Corcoran was not a common surname in Co. Leitrim in the mid-19th century. The surname was primarily found in Cork, Mayo, Kilkenny, Offaly and Roscommon. Possibly your family migrated from Roscommon way back in the 1700s.
I looked at the 1857 Griffiths Valuation head of household listing for Inishmagrath civil parish (which includes Drumkeeran) and there was one Corcoran listed, a Luke in Lisacoghil townland. Possibly a connection to your James. The RC baptismal records for Inishmagrath RC parish are only available for 1834-1839 and I checked and did not find a James Corcoran.
https://www.failteromhat.com/griffiths/leitrim/inishmagrath.htm
The 1901 census for Co. Leitrim had six Corcoran families and only one was in Drumkeeran.
http://www.census.nationalarchives.ie/pages/1901/Leitrim/Drumkeeran/Chu…
I would try to find a death record for James to see if any parental data is included.
Please consider adding his story to our XO Chronicles site and maybe someone will see a connection. https://www.irelandxo.com/ireland-xo/history-and-genealogy/ancestor-dat…
Have you considered DNA testing?
Roger McDonnell