You could try the National Archives for this sort of information. They have the transportation records for
Ireland to Australia so perhaps have court records, either that or the National Library. You can always ask them questions as to where to find this sort of information.

I see you got the information from www.familysearch.org
prison records and the third listing is a reduced charge to manslaughter. These Prison records do come from the collection at the National Archives, in Dublin.

www.nationalarchives.ie

Also in the 1901 Census are 2 George Power's very young,
one being 14 attending a school in Ballynakilly Electoral District. The other a 2 year old living with grandmother.
www.census.nationalarchives.ie

In the Griffith Valuation of Galway 1856 so your George would of been too young:

There were 10 Powers in the Parish of Ballynakill, 3 of which were in Loughatorick South.

George Powers, Parish of Ballynakill, Townland of Loughatorick South, Poor Law Union Loughrea tenant
of Anthony Nugent:

#7 herd's house and land 29 acres 3 roods 0 perches
#11f 1/10 share of 254 acres. 1 rood and 35 perches
also in #11 is a Kieran Power

Oddly although Kieran is sharing land he has no house of his own? so possibly living with George!

This would probably make Kieran/Kerin Power his brother, uncle or grandfather?

Annette Code