The headlight will always dim at idle because it's run directly off the magneto on AC. If you switch to a led taillight and turnsignals, led instrument lightbulbs you might have enough Watts left over for heated grips. You could also send the stator to Ricky Stator or Baja Designs to get rewound for higher output.
Make sure the auto decompression cable has 2-3mm free play at the end of the exhaust valve lever to work properly for easy starting. Off course the engine has to be tuned properly, good plug, valve clearance right, aircleaner clean and the carb jetted properly. It also helps tremendously to run synthetic oil in it.