I think 7-8 hours is about a good time.
A race to 9 takes about an hour or so right? Although it is 10-ball on big tables with a little tighter pocket. So maybe a little longer.
So if it comes down to hill-hill (for the first day) that's 35-34, then we might be looking at 8 hours.
Throw in some break times, maybe a dinner break, Mika whining breaks, etc. and it could be a pretty long night.