EGR Delete & a coolant filter are a must! And if the oil cooler has not been serviced then get that done as well. Nice truck!
I would buy an Insight to monitor your temps before dropping the coin to have the oil cooler serviced/replaced.
110% agree on the coolant filter, EGR delete is up to you.
The #1 thing about own a 6.0L is educating yourself on it and maintenance!