Do you have a computer that tells you elevation gain? If so, then you have a way of knowing how much climbing you have done on any given ride and can compare it to the climbing on this ride. The route profile says almost 4400 feet the first and either 3500 or 4100 the second (I'm very confused about that part!). If I were you, I'd try to do a two day training ride that involves around 60-75% or more of the distance and climbing that is on this ride. I'd be more focused on the climbing than the distance. Work up to it. Do some shorter climbs in the coming weeks.

I have found it can be quite rewarding to push yourself and see what you can accomplish. The most I had climbed as of the middle of May was 4,500 feet .. about 3 times since January. With the encouragement of my insane climber husband, I embarked on Heartbreak Hundred, a century with 8500 feet of climbing. So I almost doubled the climbing. It hurt. It was really hard. I was really slow. But I did it. And I'm so proud of myself for accomplishing it.

I think if you do some training rides with hills as a focus, you'll know within a couple of weeks of your event if it's something you are ready for. If you can figure out what the grades are like in the event and simulate the hardest climb(s), that would be great training.

I'm guessing you can do it.