I had original Kelsey-Hayes disc brakes on my '70 Duster that were manual and I liked it a lot. You definitely have to press harder than power brakes but the increased "feel" in the pedal is great. Really helps in low-traction situations (ice, etc.). I never felt like I needed more brakes either, I had enough stopping power to haul down from high speeds just as easily as any newer car. In fact I'm upgrading to '73-up disc brakes and I'll be keeping them manual.