Kiwi Girl
As I am doing research on William Bulfin the Irish Argentine writer, your quest interests me. Bulfin is quite a rare name in Ireland and they originate mostly in Co. Offaly (formerly King's County). As other posters have shown, there is a good deal of information on the internet, genealogical as well as historical - please also google William Bulfin, writer and Sir Stanislaus Bulfin. The person you are helping is almost certainly related to them, however distantly. I have tried to fit your 'John, son of William', into what I have learned so far about the Bulfins, but without success. The name William particularly, occurs very often in the genealogy. However, I discovered the following recent death notice online: you can also check it out for yourself:
The death has occurred of Francis John (Frank) BULFIN
Corrigeen, Fivealley, Birr, Offaly
Bulfin, Corrigeen, Fivealley, Birr, Co. Offaly, August 6th,2014.
There are Bulfins still resident in Corrigeen. Perhaps you might consider writing to them? Wishing you luck.
Timmol