Between leader and split ring NT 2/0 is more than adequate because in this position it is only straight pull. I also like to keep the weight of this hardware to a minimum where possible to get a better action from the lures.
I use 5/0 in the belly of the lures because they can get sideways pressure and I have seen quite a few lesser quality swivels damaged and broken.......never had it happen to NT 5/0