I am running a Phat Shaft 62/12 over a S400 that needs to be replaced. i'm not really happy with how well this set up cools. the truck is a 97 12 valve 913 pump with 4gsk TST 4 plate laser cut DV's and 435 injectors. I'd like to make around 650 or better on just motor and keep it nice and cool EGT wise for towing. I'm not real familiar with bottom turbos but i did a couple searches and a lot of reading and i'm leaning towards a K31. Am i on the right track?