I've got the original power drum brakes in my car. They are more than adequate. The pedal feel is a little different than I am used to with modern disc brakes, but it stops fast and straight, and I have not yet had any issues with brake fade, even with the big hills all around, and crappy stop and go Vancouver traffic. As long as they are properly adjusted, drum brakes are just fine for a classic car that is only seeing occasional cruising. If you plan to be driving it a lot, or have a lead foot, then it's a whole other story, and you should upgrade to disc brakes.

I used to have a 74 Dodge Power Wagon with drum brakes that I used for off-roading, and the brake fade on it was terrible. I shattered several sets of pads. That's a scary feeling!