Q. If I will convert new Bullet to old, is is possible?

Not possible because only the looks and exhaust can be converted not the engine. For old bullet engine you need an old model bullet and replace that engine with your bike engine but this will be similar to buying an old bullet from someone because there are engine and chassis number registered in RTO so if you replace new engine with old engine you need permission from RTO. Better option is to buy an Old bullet, there are many dealers of old bullets in Delhi Chandigarh, Haryana, Rajasthan. and many cities.

Old to new UCE model converted to Cast iron model type ? May be you wish to change the brake left side ? Visually you can convert technically major things are not possible like gear box & Brake position.

I think you need a doctor to check your brain.