2 things. One, why does the system data matter? There's almost nothing in common between 4.4.2 AOSP and 4.2.2 LG UI, and anything useful is already synced via Google. Second, that's a big negative even if you wanted to. Unless you want to bootloop like a pro, do NOT restore system data on a different Android API version. It's a bad idea normally but especially here. I personally use TB and just restore user apps + data.
Phone: Google Nexus 5 "hammerhead" ROM: LiquidSmooth F2FS Kernel: ElementalX 1.00
Tablet: Amazon Kindle Fire (Gen 1) "otterx" ROM: CM11-F2FS by Hashcode
Tablet: Google Nexus 10 "manta" ROM: LiquidSmooth F2FS-All Kernel: KT-Manta F2FS-All
Retired: Sprint Motorola Photon 4G "sunfire", Sprint LG G2 "LS980"