Go leaded and you should be able to squeeze a little more.
I would think bigger carbs. I was lucky in finding the carb insulators.
Did you carry out all the engine work yourself?
I am not speaking from experience; info from this site.
The dyno will be really interesting, should give me an idea where I will get to. If I ever get home to finish it.
Back on topic, I have looked at every big bore site on the net I think and no more kits for nsr's except the ones we all know about. I have spent considerable time looking for bore kits for my pink 50cc joker and my 50cc 3 wheeler gyro - 2 strokes.
They were the wifes; she came with nothing and she left with nothing.
The quest for more power continues then.