Correct me if I'm wrong, but a little trignometry using 100 feet as the base length and 35 degrees as the angle nets an opposite side length of 70. So that's a 70 foot vertical change over 100 feet or a 70% grade. Something about that just doesn't jive with me. Another way to look at it would be this. The maximum length for a bus is 40 feet. With a 40 foot bus on a 35* hill there would be a 28 foot difference in altitude between the front and the rear. I don't think 2x8's are going to make up that difference. If you park across the side hill and the bus is 8 feet long there will be a 5.6 foot difference between the height of the uphill and downhill sides.
Are we sure that wasn't a typo?