Keep reading under the steering units section, you still have a ways to go. That is a closed center orbital, which means it wont work with an automotive pump because it "closes" off the feed when there is no demand, certain death for your pump. You need an open center orbital.
Also, the only things that will affect what orbital you need/ want are your cylinder size, number of turns lock to lock you prefer (you choose when you select your cylinder and orbital) and load reactive feature. It doest care about you rigs weight or tire size any more than than the steering wheel. That would factor into your cylinder and pump choice though.
