I noticed the highest point is in Grafton; never ridden through there, but the other places at least have some rest in between!
I have a mountain rd on my compact (11-34), which has 2 more lower gears than my triple. It's a thought, if you are willing to spend the $, and can actually do this on your bike. Otherwise, if you have a 25 on the back, you can always switch it out to a 27 or 28, with either a triple or a compact.
This ride is hilly for a century. It's the kind of ride that I would just go slow and steady, i.e. go up the hills at 6 mph and not push it on the flats. However, if there's a time cut off, this might not work.