Useful information... also to be taken with a grain of salt, like everything else you read, including this post.
I really like this quote
What bore size do you need for manual brakes?
If you use anything larger than 1" then you will have an extremely hard pedal.The smaller the bore the more pressure that is output to the wheels.
I wish they told GM this before they put a 1 1/8" master on the Chevelle and GTO in 1968 with manual brakes... oh, wait, that worked out quite well. Hmmmmm. The last sentence is correct anyway, and they mean well.
It really is dependent on the caliper and the pedal ratio.
The Chevelle and GTO had some bigass calipers and a high pedal ratio, just to be clear..ish.