need help with pulley alignment-250-6 pwr steering

[69lemans]

I want to add power steering to my truck while I have it torn apart and everything is easy to get to. It's a 72 with stock 250-I6. I bought the power steering pump and pulleys from a salvage yard in another state over the phone,so I didn't see them mounted on the car they came off of,don't even know what they came off of. When I bolted everything on my engine,ALL the pulleys line up-alternator,water pump and power steering. I already had a double pulley on my crank as this is a replacement engine ,and I have the double pulley for the water pump,but is it correct that the water pump alternator and pwr stg pump should all run off the same belt? All help is appreciated.