Does the Y300 have the same storage as the G300? Also, is the final version of ART in lollipop using as much storage as the one in KitKat or more? I tried ART on my G300 a while back, and while it does eat up the internal storage rather quickly, I was able to run it for a few weeks (I only used the basic Google apps + some other apps) I switched back to Dalvik due to some bugs.
Anyway, I hope he'll consider porting it to G300 if the Y300 port goes well. :)