Of all the accessory drives, the power steering pump probably pulls about 10 hp off the front of the engine at max loads. When the wheel is straight, the pump is bypassing the pressure back to the reservoir; when you're turning the wheels is when most of the load is on the pump.
Is there a way to eliminate the power steering pump and still have power steering? Back in 1990, with its release of the NSX, Honda pioneered the electric power steering (EPS or EPAS). Many small cars, including hybrids these days, are using electric power steering racks. These small racks will draw up to 80 amps of power under full load. These power racks use the stored battery power to assist the driver in turning the wheel. This takes the load off of the front of the engine from the pump and puts it right back on the alternator! Remember, there is no free lunch-the only benefit is that the battery is a storage device and the alternator has time to refill the battery. Building an electric steering box for a full-size truck will take a small powerplant to feed it!
For the time being, we'd stick with your factory power steering pump and Saginaw 800 series P/S box. It's a tried-and-true system that works very well and we'd look for power somewhere else.
Technical questions for Kevin McClelland can be sent to him at chevyhi@sorc.com.