I ran the numbers assuming your dad lives 10 years after retiring and your mother lives 20.
With the 1135/568, the total amount received would be 204,480
With the 1064/798, the total amount received would be 223,440--resulting in $18,960 more.
Of course the problem is that you cannot predict who will live longer. My mother is 93, my father died at 79, so I am probably biased in favor of protecting the potential long term widow. I would go with the 1064/798.