Here is the charge:
22349. (a) Except as provided in Section 22356, no person may drive
a vehicle upon a highway at a speed greater than 65 miles per hour.
The fine should be in the ballpark of $321.
Had he put you down for 91 or higher, the fine would be about $435.
You can challenge the citation and go to trial, you can plead guilty and go to traffic school, you can do a combination of the two (go to trial and ask for traffic school if you lose, for instance ...). You can also start with a trial by written declaration and ask for a new trial if you lose.
Others may offer up some more specifics on any possible defense.