Neat project. I put disc brakes on a closed knuckle frontend back in 1991. This was a low budget off road only buggy. I am not recomending that anybody do this, I am just letting you know how I did it for an off road only machine. I used a half worn out brake pad on the inside and put a some shims between the inner wheel bearing and shoulder on the spindle to move the hub/rotor out a little bit. My reasoning for using the closed knuckle frontend was that I figured it would keep mud and dirt out of the axle joints and axle tubes. Somebody mentioned that these frontends don't turn as sharp, but I didn't figure that it would matter a whole lot on this machine because the frame was shortened up quite a bit. The other disadvantage of these frontends is that they have small axle joints. Here is a scan of an old picture of it.
