Need opinion from those that KNOW.

Good question.

I wouldn't spend money for the disk set up master cylinder when all it should be is a common drum master cylinder.
See the pdf here
Replacing Master Cylinder

No reason to have to guess whether the salesman or some stranger on the internet has a leg to stand on or is making it up as we type. In addition to the usual service manuals and parts books, Chrysler explained the differences in some of the sessions here
Master Technician Service Conference - Chrysler's Training for Mechanics

edit: changed first link to thread with a valid link to Brad's article pdf