I can’t speak for overheating since I haven’t actually ran the tractor yet and I’ll be using it just for pulling so I doubt it’ll get hot enough to cause an issue, but I did switch to an 8 fin impeller water pump from a turbocharged engine for added precaution.
And as far as manifolds there several different ways to go about it. You can either modify your existing manifold, use a 5.9 cummins manifold with some slight modifications , or buy a billet steel one from Leamans. I think I’ll be going the Cummins route.