Re: Manual or power drum master quest
Everything I've ever seen has a 1" bore M/C listed for both manual and power DRUM applications. For DISC, usually it's a 1" bore for manual and 1+1/8" for power.
Having said that -- when I converted my '69 from manual to power DRUM, I just added a booster and kept the old 1" master cyl. Brakes would lock up great, but were just too touchy for me -- If I had to do it over, I would strongly consider using a 1+1/8" master cyl with power drums to help "tone down" the sensitivity (you'd probably have to use a power disc master and install external residual pressure valves....)