upgrade master brake cylinder

Sorry if this has been answered, I tried to read through most of the posts. I simply want to upgrade my single jar type master cylinder on my 63 to a dual reservoir. For now I'm keeping all the brakes drums and staying manual. I'm reading the 15/16 bore being preferred but that seems to be for front discs. What's a good one for drums? I'm looking at several options on the 2660809 one inch bore. Best price I found was at piratejack.net. Thanks!