Power Steering Pump Choice

I'm in an abyss with regard to selecting a PS pump and properly matching various PS components. According to my '68 shop manual, there were three different pumps used; described as .94, .96 and 1.2 I don't know what those numbers indicate, but I'm guessing that one could be a Thompson pump, one a Federal pump, and one a Saginaw pump. The manual says that the .94 was used only with the 273 and 318 engines.
The PS gear box I will use is '73 (I think!), so the info from my '68 manual may not be applicable. And, so on and so forth......
The real question is this: I'm going to use the '73 PS gear, but I don't have a pump at all (was not on the '68 Dart when I bought it). What pump should I buy? It's going in my '68 Dart; I'm using '73 Duster K/gear/links/brakes, etc.