Your statement that Catherine McCrohan was born "near Valentia" rang a loud bell because that is how my Caherciveen relatives described the island where my ggrandmother Ellen MacCrohan/McCrohan was born and raised.
Ellen McCrohan/MacCrohan b. ca. 1835 at Bigness Island near Valentia, Cahirciveen, Co.Kerry d ca. 1930. According to the family Bigness was on the ferry route to Valentia.
Ellen McCrohan married John Buckley (a cabinet maker from Filemore, Cahirciveen) ca. 1865 and they settled in Coomletter, Cahirciveen.
Also have some info on McCrohans who went to Australia.
E-mail me if this looks familiar and you want more info.