Congrats on your find. I found that the old Norinco ammo was loaded hotter than stuff like Wolf or Monarch. It also burned much cleaner. Question, is it steel core or lead core? If it is steel core, you got one hell of a deal!
Sadly, I lost about 1,100 rounds of Norinco in Hurricane Rita. I left the old crate at my grandparent's house to have an offsite storage (i.e. to keep me from shooting it all) and the floods of Rita took their toll on the copper washed steel. Of that 1,100, about 700 were "rescued" but upon trying them out, they cause short stroking, if they even fire at all. I guess the floods took their toll on the powder within. I am still keeping the remaining rounds for plinking, but in no cases would I ever consider it for SHTF due to the fact that it doesn't always go "bang" every time and every 3 out of 30 rounds short stroke my MAK-90.