There is a trade off swapping masters. The cars usually came with a small bore master so that the pedal effort would be low, and the trade off is longer pedal travel. Think of a hydraulic jack, same principal. Great for Grandma, bad for a hot rod. Using a larger bore master fills the calipers and wheel cylinders quicker, thus less pedal travel, but the trade off is more pedal effort. But when we are using a power booster, the increased effort is negligible. That's why non-power brakes use a tiny bore master, like 7/8", and power discs use 1+ 1/8".