If it is a 800 series box, then yes, you need the pitman arm for a Malibu/Monte Carlo/etc. with 800 box...but...
Is it this box? It looks to be an 800 series box.
redheadsteeringgears.com
Note that the pitman arm for a Camaro or S10 is different than the one you need.
This article states some sector shafts have 4 blind splines instead of 3. When you stated "4 master", is that what you are referring to? If so, the Malibu 800 pitman arm won't fit, and I don't think you will be able to use that box.
Our comprehensive guide will help you identify your power steering gearbox. We sell & service 5 different Saginaw gearboxes: Saginaw 800/808, 708, GMT & Ford.
leepowersteering.com
This part states it has 4 master splines and is for the 800 box, so contradicts the Lee article. You may be in luck, if the diameter and spline match your box.
www.medievalchassis.com
I don't know how the stops in your Jeep box differ from the 1983 G body box. If the stops are tighter, you will have a reduced turning radius.
Sorry for the extraneous questions and data; there are too many unknowns regarding the Jeep box.