Manual disc brakes vs power disc brakes questions

I never said all cars need a 1.125 bore MC. I merely stated what worked for me. If that doesn't fit with your thoughts, who cares? You have a habit of pouncing on other posters, as if you're the only one who is right. Not the first time you've done it to me. I don't agree with you. I know what worked for me. You didn't see me puffing about how wrong you are. If you don't like what I think, state your opinion, and move on.

I "pounce" on misinformation. And in addition to saying a 1.125" master cylinder worked for you, you also suggested that a 15/16" master cylinder won't push enough fluid to run 2.75" calipers on an A-body. And that is misinformation. It's actually wrong. I know that because I've run that exact combination, and it works great. I also never said a 1.125" master cylinder wouldn't work. I said it wasn't needed, and it isn't. And on an A-body I don't think a lot of people would be happy with the pedal feel a 1-1/8" master cylinder would give, but that's my opinion. And as I've said several times, any master cylinder from 15/16" to 1-1/32" will work just fine on an A body, anything in that range will stop the car just fine. The difference within that range basically comes down to pedal feel, and that's an opinion.

What works on a '64 Fury and what works on an A body aren't necessarily the same thing. The fact that the brake pedal hit the floor on your '64 Fury with a 15/16" master tells you everything you need to know. On an A-body a 15/16" master cylinder works great. The differences in the braking systems between an A-body and your '64 Fury are apparently too great for that information to be relevant.