Bore size for Manual brakes

What brakes are we talking about?

.937" is a 15/16" master cylinder, which is actually what I prefer for most manual disks on these cars. A larger bore will give you a harder pedal effort, but will take less travel to engage the brakes. The smaller bore means a lower pedal effort, but it also means that you need more pedal travel. The smaller bore also produces higher line pressure, so, you actually get more clamp force at the calipers. But again, it will take a bit more pedal travel to create that.

My personal opinion is that the factory 1-1/32" master cylinders are a bit too large for manual brakes on an A-body, they give a high/hard pedal that makes it tougher to modulate the brakes- they're much more on/off with that size. 15/16" gives a little more pedal travel, so you get a bit finer control over your braking force. But, you need more travel to fully engage the brakes so it can make it a little more challenging to just slam- lock up the brakes. Of course, you don't WANT the brakes locked for maximum braking, but you still need to be able to do it.

The difference between 1" and 15/16" is noticeable, but whether one is better than the other is more about preference than performance. And of course it does depend on the caliper bore size too, so it matters which brakes you have.