Ok, I couldnt see the pictures from work. That's an early Kos frame. He changed the logo stickers from that to a more traditional times roman style font later ('91-'92, I had several friends who had them and rode with Nick pretty regularly). I'd place it late '80's.
What's also interesting is the fork is not classic Nick straight blade, so this also put's it early.
Enjoy! he made great bikes and was a fixture in the Nor-Cal, annadel group for years.