Hi Geoff
Fellow Aussie here, tracing my own family.
May I suggest looking at the shipping records. I know about the Kapunda, I am glad your family arrived here safely. With shipping records, we have the Australian ones, BUT.... remember that Australia was not a Country until 1901, so some records ARE on the national archives here but there are records held by the Colonial Secretrary - that means ALL paperwork for every area of Australia are held by NSW too.
BUT... I would use the shipping records from the UK - England... because they coordinated the shipping, even for ships leaving Dublin. There are always two shipping records - outgoing and incoming. The outgoing shipping records seem to be more reliable - they are obviously familiar with the geographical locations in Ireland so have recorded more accurate data. That would be my first goto because you could be given exact locations to start your search