If the officer used Laser, then not only would he have visually estimated your speed (meaning he was looking directly at you), but he can also see which vehicle the red pointer is on through his viewfinder, and so your claim that it wasn't you isn't likely to hold up or have any weight at all.
34 over is not going to be easily overcome... But you can try I guess. The other problem with 34 over is that while you maybe eligible for traffic school meaning you have not had a violation get held confidential as a result of completing traffic school within the 18 months prior to this violation, most judges will not allow a traffic school option for that big a speed differential. In fact the rules of court set that break point at 25. And you are 9 over that. So while it maybe true the cop said he'll confirm that you are eligible, your violation may not qualify if the judge decides to withhold that option.
Furthermore, you will have to decide if you want to fight it, or if you want to plead guilty at the arraignment and take traffic school simply because if you do choose to fight it, and assuming the judge would have allowed you the traffic school option at the arraignment, the chances that he/she will offer you the same after trial are slim to none.
Now, to make an educated decision as to whether you should fight it or not, you'll have to request and post a copy of the most recent Engineering & Traffic Survey for that stretch of highway which you can obtain from either Caltrans or more probably from the Public Works Department of the city of San Juan Capistrano.
Once you've obtained that, scan the document in its entirety, upload it to an image hosting website, and come back to this thread and post the [img] links you can obtain from that host site, and someone will chime in with more info which you can then use to decide if you should fight or not.

