I, too, have some IL Killoran's.I don't have much info, but maybe someone will be able to make a connection.
1920 IL federal census: Killoran, Mary E. age 65 widow Mary A. age 37 single Nellie T. age 32 single Loretta age 22 single Family residing at 123 Carroll St., Freeport, IL
Mary E. stated she was born in IL, and that both of her parents were born in Ireland.
All 3 of her daughters are listed as having been born in IL and their father as having been born in Ireland.
Loretta Killoran was my step-father's mother.She married James Hannah, Jr., who lived on State St. in Freeport.James Jr. was the son of James Sr. and Maud Clark Hannah. She (Loretta) died young, about 1940.I think her father may have been Thomas Killoran.My step-dad thinks the family came to Freeport from Amboy, IL.
Nellie Killoran (Nona) died about 1956 in Freeport.
I am just getting started on this branch of the family.If this connects with anyone I'd be happy to hear from you.