Pretty good.
If you want to throw even more meat towards the Irish, have Brian Ború and his family not die at the Battle of Clontarf, which unifies Ireland for at least a time under a strong dynasty. A stronger Ireland at the time can place more energy into expanding it's influence in Scotland, so instead of the previously mentioned Normanisation in Scotland, you get Gaelicisation as the Scots turn towards the Irish as a power based instead of the 3/4/5 English and Welsh states on the go. In fact that would result in "Alba" rather than "Scotland".
Brian Boru was seventy-three as of Contarf (based on the Encylopedia Brittanica), and he did have at least one surviving son - Donnchadh mac Briain, historically king of Munster.
Which is to say, I don't see why Brian living is such a surefire path to anything.
I'm not saying it couldn't be done, but I think even if the High Kingship passes to one of Brian's sons that the whole issue of "Ireland's (High) Kings have a lot on their plate
dealing with Ireland." is going to significantly limit the amount of influence they can project into Scotland.
Meanwhile, what do they have to offer from the standpoint of why anyone would look to Ireland for ways of strengthening their power/their kingdom?
Even if somehow you get a Divided England scenario, which seems like it would not last very long.