For reference; that would be a 59% grade. I think that goes beyond the hors categorie rating system and starts moving into the UIAA scale.

My longest hill climb is a 2.25 miler with about 600' of gain. 5% if it was a constant grade, but there's 3 sections where it goes to about 8%, and a couple sections where it drops (thankfully) to 3% or below. I have the option for a 0.4mi hill at 14.7%, or about 300' of gain in just under a half mile.