What should be the prime voltage on the O2 for a 95z with full exhaust and k&n cai under full throttle?

 

Not sure what "prime voltage" means... but in general, the stock, narrow-band O2 sensors are not accurate enough at the richer mixtures you encounter at WOT (power enrichment mode) for there to be a single answer to your question. You could see anywhere from 850-950mV. The operating temperature of the sensor will change the mV readings more than a fairly large change in A/F ratio.

In closed loop, they are very accurate, and will produce 450mV at 14.7:1. But at the 11.7:1 that the stock PCM program typically targets at WOT, you will not be able to get an accurate reading.