For some reason the nj4 doesn't work well with the ROM, and to me there's not a big difference between nj4,nc1 blah blah. I'm still on nc1. You can just flash the stock root nc1, then flash the kernel in odin, install safestrap, then flash the new ROM.
I am on NC1 and this newest Pure Nexus is working great. All my xposed modules are running and have not had any ghost vibrations yet.