Seeing the discussion elsewhere that Zvezda are going to release a kit of the 777-300 reminds me to question my sanity in upgrading the Minicraft 777-200 to a -300. Of course it never occurred to me that anyone would ever kit a -300 so it seemed that the only way to get one was to get out the razor saw and other tools, buy the BraZ Models conversion kit and get to work. After my troubles with the 767 upgrade kit I was not confident in using this conversion kit but it turned out to work okay. The engines also came from BraZ models but I cannot remember now who made the new wingtips. All were purchased from Airline Hobby supplies. But if I were you I'd wait and see how the new Zvezda kit looks when it arrives.
The decals for the -300 come from Ric Warcup who makes quite a few decals for Virgin Australia airliners.