There's about 6000ft of climbing over 64 miles so it's fairly evil but certainly doable. Here's my data from the 2010 route (I wasn't in the best shape for the event) http://connect.garmin.com/activity/45541672 . I'd go for it. You have plenty of time to get into climbing shape for the ride. The 100k was a pretty laid back event with a reasonable start time too (9am). Work climbing into your weekly routine and you'll have no problem doing it.