I agree, 1916 Dublin would be great. But if you ask me I think the best time would be the 60s/70s. At this time the 'movement' is just getting good.
I am no scripter or modder but the hardest part of the mod might be the terrain and place names.
As alot of the textures and skins are available,
I saw somewhere, textures for British infantry and some Infantry support vehicles. The IRA could be civilian textures with the appropriate weapons, such as Ak47s, Thompsons, Armalites, RPGs, Galils, and, nearer to the 80s : Barrett Light 50s!!! ;D
We'd also need a ton of script for timed devices, car bombs, mortars etc.