I am still thinking I need a few longer rides if only to get my butt/back/body ready for a 14 hour ride.
With your experience level (according to your post details) you'll have no problem. If you use
the same good judgement that allowed for finishing centuries - all will be fine.
The more probable scenario - is to do something stupid early on the ride - and then suffer the consequences towards the end of the ride.
Much of distance cycling success comes from the skill of pacing yourself as well as fueling and resting in timely and efficient intervals.
Good luck......