China has hundreds of aircraft with latest gen radars. It can send a few to Iran via Pakistan. Again, no one is flying these aircraft; they are parked on the ground just to use their radar to provide targeting info.
As for hooking them up to Iranian SAMs, it's just a matter of writing new software. Totally not impossible, especially if this war is supposed to last weeks as Israel claims.
The reason Israel managed to kill its enemies is because they think out of the box (pagers, drones, etc.). We need to start getting creative and find out way to make things work instead of finding excuses why they won't.