I've just put a 17inch rear on my Nc also put a rs250 rear shock on it looks like it's sitting a lot lower than it was I know I can screw the bottom fork on the shock out a bit but is there anything else I need to do. Cheers stu

Ideally you'll need the NC35 dogbone or you can modify the NC30 link to achieve the same result.
Info is in this thread.