The Amtrak century doesn't have that much climbing. I rode it for the first time last year and it was one of the easier centuries I have done. Although I heard there is usually a tail wind to make it easier. We had a head wind last year. Im looking forward to this years ride.

The only big hill is torrey pines which I don't think is that bad, but it is 75-80 miles into the ride if I remember correctly. 70 miles a few weeks before is probably fine. There should be plenty of people to ride with to make things easier.