check the reciever specs if its 8 ohms compatible, personally i think its panasonics way of making an 85 watts system sound more powerful then it really is.
To keep it simple, 8-ohm is fine! Going "down in ohms" is where you might see a problem.
The Panny-200 really dose have a pretty strong amp section and probley will drive even a 4-ohm load with out a problem, ("Stereo")! But check your manual if you decied to change speakers that might fall into ~{a "lower" than 6-ohm load}~!!!!
Myo is right, the 6-ohm power output spec at 1-KHz,,, is to help make the power output rating look better....
Panny is not the only brand to use these type power rating tactics and not use what I and most like to see, which would look something like this:
Simulation brand -X
Stereo L-R 130-watts "with both channels driven" 20-Hz to 20-Khz into 8-ohms @ .01% distortion
All Channels ~ DPL DD DTS, etc. 100-watts "with all channels driven" 20-Hz to 20-Khz into 8-ohms @ .01% distortion
This type of spec tells a much more accurate story of the receivers-amp section power capabilitys into a 8-ohm load.
So enjoy your 8-ohm speakers their no problem for the Panny!