As a member of Conradh na Gaeilge, Croabh Curtin I am trying to track down any works for a reading, or staging, that are relevant to 1916 and which are in Irish. Our merry band would like to attempt a performance of some kind next year. And, sadly, I’m having trouble locating any texts. Foir orainn, le do thoil!
With my limited knowledge on the subject, the only work I’m aware of is the film Mise Éire. It’s mostly narrated by one person so I’m not sure it would make the best stage play, but you might be able to get creative and adapt it somehow. Go n-éírí an t-ádh leat!