If the lobes were damaged shouldn't you have replaced the lifters??
I have played with a few LS motors and they really respond to a performance cam. The problem with a 2500 HD is you want to retain the low end torque so you have to stay on the lower end of a "Performance cam" They make plenty of smaller cams for trucks and once my warranty is up I just may do this as well. I think TSP sells 3 versions of VVT cams. They are really meant for Camaros with the 6.2 LS3 but can be put into a 6.0. With a 6000+ lb truck meant for towing I would be hesitant to go with their largest one. Stage 1 is probably what you want if you tow at all. With a tune, headers and mild cam I think you could pull 40 + hp from the 6.0. Ask TSP they will give you good advise. I am guessing you may have to swap valve springs for the higher lift of the cam.