I use non power disk brakes on the '37. Yes it takes a little effort to stop, but once you drive a while you get used to it. GM sold '70 Chevelle's and Corvette's with manual disk. I used a Chevelle master cylinder on my drag race car with manual disk and it stopped just fine from 122 mph time after time.
With the right lever ratio and master cylinder bore diameter, you can minimize the effort.
Joe
