Help from GMC/Chevy 1500 6.2L owners with NHT package.

I can attest to the fact that the 6.0 is made for running under heavy loads (say towing a 10k trailer) at high rpms in hot conditions for long periods of time over and over again with no high heat consequences.
I have owned 3 of them and I say they are bullet proof and a proven gasser drive train for towing.
There is a reason GM keeps the iron block in the HD line.