For those talking about building Kitkat but have lost the recovery to do so.... I'm pretty sure TWRP 6.3.2.0 I think it was can flash KitKat roms. I know we had a TWRP recovery at some point for this phone, so maybe it can be updated to flash Kitkat? And there are partitioning files that can be modified to allow a bigger system and a smaller data partition, just add link2sd by default then.