Smaller calves can use this system, if a small, shallow tank is placed under the pump to collect overrun water. This overrun water can then be used by a calf, smaller that 400 lbs. The overrun water comes when the cow pumps the nose pump and extra water that cannot be held in the nose pump reservoir runs over the reservoir into the small shallow tank. There are several companies manufacturing nose pumps. You can get the pump in cast iron and cast aluminum.
Some pumps come with three bolt holes for holding the pump in place, one in front and two in back.
Some come with two bolt holes up front and two in back. I have not seen where one brand had an advantage over another brand other than the aluminum models are lighter to handle. Manufacturers have a little different instruction with their pumps. Some companies say it is possible to deliver water to 300 ft. Some say with a vertical lift of 25 ft.