Add as much weight as you can carry safely , there is no penalty for too much weight
the international long track has a 5 mile run up and you will probably cruise a mile or 2 before accellerating , timeing your run to reach top speed just before the timed mile .
I have the swingarm full of lead shot, a weight box filling the gap of the 8" swingarm , and a lead ingot on each side of the bike at the rear
I am of the firm believe you can have the weight too low and cause handling issues , i like to keep the weight at a similar distribution above and below the axle line as the original bike