http://www.mapmytri.com/routes/view/37235078
http://www.mapmytri.com/routes/view/38692482
http://www.mapmytri.com/routes/view/37235594

Does not look particularly challenging for a regular road gearing. If I was planning to do this ride I would just run 71" and call it a day.

But I bet 75"/67" would be more fun, even if it required flipping the wheel a couple times.