Disc or drum

There is more surface area with drums than discs... Which is exactly why it takes less line pressure to make them work.
On high performance B Bodies, they used 10 inch drums on the back when discs were ordered to maintain some balance. The normal 11 inch rear drums on those cars would overwhelm the disc brakes and cause the rears to lock.
From a historic perspective, NASCAR did not allow disc brakes on their Grand National cars until around 1975. Some people, like Richard Petty stuck with drums until the early 80s.
As someone who has been swapping disc brakes for drums on my own cars since the 70s, I can say first hand that I have never experienced any sort of braking issues from the "downgrade"... But then again, I don't hot lap my cars on autocross tracks.