I usually cook mine at about 250-260, and it takes roughly only about 1 hr / lb, give or take. 240, perhaps an hour and 10 minutes, so you're looking at about 9 to 9.5 hours, IF that long.
Yes, you're on the right path.
Hance - Lake Dogs Cooking Team - MiM/MBN/GBA CBJ and comp cook
Lake Sinclair, GA (strategically about an hour from darn near anywhere)
Started competing in chili cookoffs back in the 1990's and have competed in more than I care to count. I became a CBJ in MiM in 2005, then MBN and in GBA in 2010. I've probably judged 130+- BBQ comps (sanctioned and unsanctioned) over this time. That said, I really enjoy competing more than I enjoy judging, and hope to get back to doing 4 or 5 a year in the near future.