I think the last viable and concrete Irish-American racketeer leader to come outta the K&A, would have to be John Berkery in the 1980s. Well, unless you count the vaguely Irish meth guys that were left with the remnants after he went AWOL.

Everything else is really just insubstantial rumormongering.

Altho, I'm sure there's still little crews and independent crooks in the Northeast of Irish descent.