The front brake never worked well from new. From a vintage stand point, butchering the front for a lousy ty is the 8 th sin. Problem riders now a days do not understand vintage bike set up. The bikes need to be jetted well, and we ran no idle. With it not having an idle(remember no clutch was used)once the throttle was closed the heavy flywheel kept it chugging along at very slow rpms and only took just a crack of the throttle to start hitting again. With this set up it did not take all that mauch braking to slowly work your way down even the steepest drops.
There are several methods to get a brake better, but you need to start off with fresh pads, new cable and a quality lever before anything else.