Have the same problem with my 85 22RE (cam, big valves, higher compression, & header) every smog. My NOX were at 1200. So what I did is tee into the vacuum line that goes to the EGR valve then tee in to the ported vacuum line off the throttle body & hide the vacuum line under the intake plenum. What this does is at part throttle the ported vacuum source applies more vacuum to the EGR valve than normal causing the EGR vavle to open more & that = less NOX. After the smog I take the vacuum line off and throw it in my glove box for next time. Been doing this for the last 8 years. Also what helps is making sure that the cat is real hot. I sit outside the smog shop & run the engine at 2000 RPMs untill he is ready to smog it. Good luck.