any idea where I can get new camshaft for zzr400? or maybe the one from zzr600 will fit?

The spacings for the inlet cam are slightly wider on the 600, but cams can be used. I run a modified set of ZZR600D cams in my ZRX400/650 hybrid, same durations just more lift. Which cam are you needing? I've got a spare set of ZRX400 cams here which will fit, these are the same as ZZR600D model timing figures, the 600E had much longer durations, and would need the inlet modifying to fit the 400.