If you want a quick and easy way to try out the upcoming version of Android, Android L on your Nexus 7 2013 you are in luck. MultiRom has put together a quick port for this device and it can be installed via custom recovery. I would highly recommend that you first make a complete nandroid backup since Android L doesn't seem to be as stable as the current Android 4.4.4 build. If you want to try it out head the link below if it doesn't work out for you then just restore that nandroid backup.
Via XDA