If I were in your shoes I would be worrying about trashing my new bike. Most likely while going down.
If you want to know how your gearing will work - find someone who has ridden the event and ask them what they used.
If you can't find anyone - look around at the starting line - If everyone else is using a triple - 34-40s = you'll probably be walking some of the way........
Good luck - quit worrying - and get ready to savor a life-changing - awe-inspiring ride of your life......