Happy to help Katherine. The Masterson book is now sold at Berniesworld. Its really cds. The records are colllated by father/mother and show all children born to them by birth registration and baptism (sometimes with the godparents noted). Really good and helped me a lot to look at them as families. It also allows you to rule out namesakes (kids who died early and then their name was given to another child born later). You have to slightly ignore the birth date - its really when the birth was registered. Baptism was the important one otherwise as you know they weren't put in the church if they died but down the shore in the 'killini'.
You could of course do this all yourself for nothing on family search or pay as you go on rootsireland. The 1901/1911 census returns also sometime indicate who the next generation back were. For example, next to my great grandfather's name is his own father's name put in brackets. The census collectors sometimes respected the older Gealic oral tradition!!
The Masterson book will only take you back to 1864.
A free source is also the military pension records published online 2 years ago by the Irish government: lists the claimants by their local brigade and rank for a military pension from the War of Independence. All the Achill companies are listed.
My mum is from Achill but brought up in Scotland: only saw her brothers when they came to Scotland for the 'tattie howkin!! They were a mix of Gallaghers from the Valley and my Grandfather was Johnny Masterson from Sraheens - known as Johnny 'Owen'. There were Kilbanes on his side through one of his uncles: she was another Katherine Kilbane! They all worked in Scotland or went to Cleveland.
There are some boards on Ancestry that discuss the Achill Kilbanes. You'd find it easy if you did a Google on the 'achill Kilbanes'. There are a couple of people on there who might scan you a copy of the records for the people of interest to you if you enquire nicely.
#Love Achill