You'd do the 60 no prollem. With a group of pacers, motivation from others around you, you'll do the 60. Just DO NOT start out to fast. 90% of the others will make that rookie mistake! Ya get hyped and tend to shoot off the line. DON'T DO IT! You'll catch all them rider a few miles down the road.
I bet your ride report says you did the 60 ride. A 60 miler is a 40 miler with one more rest stop!