I would be careful there, if you plan on porting roms, try and stick with D802 and yes you need a kernel, however thats for ports
Most custom roms support our beloved D803 now anyway so really no need to port. So find a rom you like and most like a D803 variant will be available.
the hottest atm are lollipop roms. Currently running AICP nightlies. There is an extra step as lollipop roms are based on JB sources and require a JB baseband(radio, modem) for rotation to work. Be sure to bavk up efs when missing with basebands and stick with D803. Good luck. cheers
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