What is Needed to Convert Manual to Power-Assist with 9-inch Drums

I am pretty sure that power brakes were available with the small-bolt 9-inch drums on late-sixties Darts or Valiants. I see listings for master cyls. but they differ between manual or power. Can someone elaborate? I suspect it has something to do with how M.C. interfaces with front face of booster. Also, can the wider/shallower Midland style booster be used (depending on attachment and clearances)? Does prop. valve need to be replaced? Are there any links available? Finally, I have no need or desire to 'upgrade' to front discs - - just looking for a little less foot effort when stopping (although 16 yr.old daughter has driven over 300 miles past four weeks with no complaints).