You can install this over Stock 4.1.2 JZO54K.
How do I install this?
1. If you are on any custom ROM, flash the 4.1.2 factory image.
2. Then flash CWM.
3. Reboot and copy the zip to your device.
4. Reboot into recovery and flash the zip.
5. Enjoy your Android 4.2
Will be posting a full flashable zip soon too.