Ninja 250's one of best bikes to learn on track! Lightweight and nimble, teaches you very quickly! I had reached plateau with my previous CBR600RR and picked up 250 for racing. I ended breaking through my previous limits and got so much faster with it!
Having actually used all these tyres mentioned, I really do prefer Shinko SR740/741 for Ninjette over Sport Demons. Much newer and better technology & rubber compounds. Personally, I prefer to stick with factory 80-series sizes, bike feels really slow handling and numb with taller 90-series tyres.
Realistically for your 1st 2-yrs on track, tyres won't make that much different as you'll be learning and won't be anywhere close to limits of any tyre. Off the shelf street tyres now are way better than all-out race tyres from couple decades ago when these bikes 1st came out.
Here I am at Laguna Seca on Ninja 250 with Shinko tyres. A little too gung-ho on 1st lap with cold-tyres, but very forgiving set-up.
Link to original page on YouTube.
After morning warm-up, I usually go out in fastest A-group for afternoon. Skip ahead to 6:00 for back & forth action with my buddy Steve on Ninja 300. He usually races 600 Superbike class but rented quieter bike due to noise regulations. He mentioned it was scary how much faster little bikes can go around corners with extreme lean angles.
Link to original page on YouTube.