I'm thinking 5-6 hours also. what i do with a bone in is remove the bone ( try to make the roast as round as possible in that case) or remove most of the way, oil and season it all the way around and then tie the bones back around the meat to give the bone-in flavor. i season with a heavy spog and olive oil or a very similar rub to spog (like instead of salt using Worcestershire sauce or something in which you wouldn't need the oil). just remember a big piece of met like that will take a ton of seasoning and will take a good 8-12 hours to absorb.(over night in the firdge works fine)
as for the cook i would have a remote probe like a maverick or something similar in it the whole time. the IT can get away from you in a hurry if you don't stay on top of it. its not like a brisket where a few IT doesn't matter much. give yourself time for resting a piece that big i would suggest at least an hour maybe two. count on 8-10 degrees carry over in IT when you cook so if you want to end at 135 degrees pull at 125 wrap and let rest. if you can put a pan under the roast and make a smokey jus, i recommend Chef Jimmy j's smokey jus, i omit the wine in the recipe and it comes out fantastic but you can add to your taste if you desire.
Chef Jimmy's Au Jus
1- Lg Onion,
4-5 Carrots,
3-4 Ribs Celery
3-4 Peeled Cloves of Garlic
Toss them in a pan under the Beef, and let the whole deal Smoke for one hour,
THEN add 4-6 Cups Beef Broth,
2 Tbs Tomato Paste,
1/2 tsp Dry Thyme (4-5 sprigs Fresh)
1-2 ea Bay leaf
Finish the Smoking process to the IT you want.
While the Roast is resting, dump the pan juices veggies and all into a 2-3Qt Sauce pot and add 1Cup Red Wine, something you like to drink, and bring the Jus to a boil, lower the heat and simmer 20-30 minutes. Strain out the veggies and let the Jus rest a minute or so for the Fat to rise. Skim off the bulk of the fat then using strips of paper towel laid on top of the Jus then quickly removed, take off the last little bit of fat.
The purpose of Smoking the Vegetable for 1 hour before adding the Broth and Herbs is...The Smoked vegetables Roast in the Dry heat concentrating their Flavors and Sweetness giving the finished Jus a Richer, Deeper, Full Flavor.
smokey jus
prepping the raost with lots of seasoning...
smoking on the smoker with a probe...
wall to wall pink...
Lots of times i smoke the roast to med rare and slice after a rest and sear the edges off to the doneness the person prefers. for my father in law i have to put under the broiler until its about burnt and serve with A1 sauce...heathen...
Hope this helps...if there anything i can do to help PM me...
Happy Smoking,
phatbac (Aaron)