I'm doing up a 69 TS250 for dirt track duties (pre 78 250 class at my local track). To keep the weight down, I've replaced the steel forks with '77 TS250 forks and the steel rim for the al hoop. But I kept the twin leader brake by 'adapting' and wiring in the original and the later TS spokes. Saved about six kg as a result. The brake works quite well, but may replace the shoes with more modern ones for even better bite.
Also replace the rear wheel with an early 70's MX wheel/brake setup - another six kg saved.
Its got an early TM top end, carb and aftermarket chamber for a few extra horsies. Still got original shocks (with damping!), seat and tank. And is still a heavy beast. But looks pretty cool.