Manual Disc/Drum Master cylinder and stock manual push rod

I used a stock manual drum pushrod with a cast iron 7/8 bore MC. Worked fine. Make sure you have some sort of retainer to hold the pushrod in the MC. The typical one is the small rubber sleeve. There is anot her style (older) that is retained with screws.

If if was me, I'd get a MC for a 73-75 power brake A body car but run it manually. BTDT and they're cheap.