I assume this is a Chevy with a standard power steering pump. It sounds like the relief valve might have been leaking due to trash resulting in lower pressure and higher temp.
I add shims to the relief spring pack to increase the pressure and steering capacity. I also drill out the flow control valve a bit to increase flow and response, but too much and the pump will cavitate. I can dig up the details and post if interested.
I also run a hydraulic system oil cooler about half the size of my radiator and it has a dedicated electric fan, but this system also drives a hydraulic winch.