You will need to find the PS enclosure used or in your case at least a whole pump with the pulley first. I think they are called a banjo pump by some. Rebuilt pumps can be purchased most anywhere. You may want to look at an AGR pump to go with the neew steering box.
Do you have the 2 metal brackets that would bolt to the pump and the long bolt that are typicly attached?
Ebay might be your best bet but I would guess some around here might have what you need.