It has to be 4.4.2 version and its very easy to port it because you have just to replace boot.img and thats it but we have till now on every 4.4.2 a grand 2 ported rom
i booted up 4.4.4 rom on s3 neo single sim but it has a lot of bugs cuz they are difrent android os version 4.4.4 vs 4.4.2 xD