Nearly bought one a few years ago. Sailed it a few times - went like a train to windward but has a narrow beam so was a bit of a handfull in heavier winds when going downwind.
Accomodation was a bit basic but sound enough.
Would have bought it but found a pristine refitted Jaguar 27 which won the day.
I'm sure some were built in Ireland so don't know what their build quality was like.
If you find a nice one would be worth getting.
there are a lot of shipman 28s in dublin bay area clubs. if you contacted howth yacht club the may be able to put you in touch with the class association.
good luck.
nac