how to convert samsung ?? i9500 to i9505

hello friend , i have been seraching alot about convert any samsung firmware to other model but really cant find any soultion or sumeone helping me out there ,, plz im requsting
any of you.. i need to know what basis i should know about converting any model i mean
do i need to know chip b4 do anything!!

chipe ??
firmware verison ??
model ??

plz looking for positive reply
hopepully i ill get hlep :rolleyes::cool: