Restoration question

Welcome to the site, my vote is for disc brakes too.
However, I would go with the bbp discs from a '73 and up a-body, and put bbp axles in the rear.
They are better than the sbp brakes and the parts are a lot cheaper and easier to find to boot.
I would also keep the manual brakes, just use the 15/16'' pistoned master cylinder.
IF you are doing a TRUE restoration, keep the 10'' drum brakes and manual master it came with and rebuild both, they really aren't as bad as some people think when they are in good working order..........