If your not bothered about mod'ing it too far the only things you really need are.

Ditch the oil pump and tank. It gives you alot more space and makes almost everything easyer to work on.

Get an SS/SP HRC harness and delimiter. This will let you ditch the lights and makes the wiring very simple.

Find SE/SP forks and shock, make sure they are in good nick.

The rest of your money spend on brake seals and chain and sprockets. Its easyer to find lost hp though getting everything running sweet like sticking brakes and worn out chains than it is getting inside the motor.

After that you could a lightened fly wheel and other such lightened parts from NSR-World.
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If I have to take the carbs off once more...