I would go with power brakes when upgrading to discs on a daily driver.
Discs require more effort than drums so you will have to get even bigger leg muscles if you go the manual disc route.
My '65 Valiant has non power Kelsey Hayes discs from the factory. They do a good job of stopping the car but the pedal requires a lot of pressure so you don't get the feeling of having good brakes until you really step on it..