If I was going to be doing an NIR layout, it would be Belfast port. I think it would make quite a nice fictitious layout, with the m2/m3 bridge making a scenic break to hide the fiddle yard! But now that I come to think of it, there isn't that much that I'd nee... most of if not all of the locos for the freight trains were provided by IE I think, although I may be wrong... so if I had 208 and 112, a rake of gatwicks, maybe in sometime a class 3000/4000 repaint as UP suggested, and NIR signs and buildings, then I think I could preserve an NIR feel to the layout!