Congrats on deciding to do a century! If you've ridden 65 miles, you're there. I'll also say that there isn't a lot written about century training--at least not as much detail as running marathons.
I train to 65 miles-ish or a metric century (just like the longest run for a marathon is 20 of the 26.2) then go for it. The adrenaline of the crowd will carry you through. You're in the preparation stage. I would try to get a few short rides during the week, if possible. If you don't normally ride a lot of hills, try to find some hillier routes for practice. You need to focus on hydration and nutrition at this point (ie. fatigue at 65 is you running out of fuel!). What clothing will be comfortable and setting up your bike to carry enough tubes, tires, snacks and water to get you to the rest stops.
I received a lot of good advice on this thread a few years ago:http://forums.teamestrogen.com/showt...hamair+century
Team Estrogen also has an article here:
http://www.teamestrogen.com/content/community
And SAG will take you back to the start line (when they can. It may be a long ride--I've heard). I never plan to bail, but it's nice to know they are there if you can't finish. Maybe call ahead and ask how they feel about it.
I will say, my BIL did the century with me and his longest ride was 40. I don't recommend and it wasn't planned that way. However, at the time he was riding 1-1.5 hours a day so he had a good base.
Here was our ride report:
http://forums.teamestrogen.com/showt...ailnet+century