[72SB]

I believe MC are specific to power or manual, not aware of with or without filler slug unless the appropriate MC for power needs one (has recessed hole for it)

My manual to power conversions in my 67 and 72 I had to get "power" MC and booster combo. Each came with adjustable PR (threaded) to adjust at pedal end. I had to cut the threaded rod some on the Right Stuff kit but not the CPP kit. Cutting the rod was no big deal and I assume the kit had multiple applications, so they made the rod longer than my particular set up.

As mentioned, you need about 1/4" of free pedal travel before it engages the MC through booster so no pressure remains on the MC with foot off the brake pedal