If I am not mistaken chrysler used two different P/S pumps for different years.
One with the round top filler neck on the reservoir was made by thompson, and the one with the egg shaped filler neck was a saginaw. Saginaw pumps and parts were more available when I was looking for parts for the thompson pump on my 65 coronet, so I had to get a rebuild kit and rebuild it myself.
I will post a link to a rebuilt pump from napa that i pulled up for a 67 dart maybe it is what you need.
http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?A=NSP816666_0186429439&An=599001+101967+50020+2020014+4020037+5999999&Ar=AND(P_RecType%3aA)
Hope that will help you out.
Matt