Wow! That's one honkin' brisket! I dunno, I've always allowed 2hrs per pound so it will definitely be an overnight cook. I'd starting for the overnight at 200F, probably around 6 - 7 pm, and checking in the am to see what it's doing. I'd guess increasing to 225 in the early am, and watching the IT as it goes through the stall. If you can place multiple therms, more info is better. I'd suggest avoiding the urge to kick up the temp to speed up cooking, with a brisket that heavy, you risk dry outside meat before the internal is tender.
Another thought: You might separate the point and do that separately later, and just do the flat. I think that's what I'd do.