The bike I had it on it came as standard, twin disks on the front, one operated with the back brake, the other on the front brake leaver.
The combined brake on the rear brake pedal would be the minimum I would use if I wanted clean bars, had a chopper once with a stupid 70's front drum about 4" totally useless, and very dangerous, I was to frightened to go anywhere on it because I knew I couldn't stop in a hurry!