If this is a pork shoulder you should separated the group of muscles at the joint. This will give you a butt (upper shoulder), and the picnic cut (lower leg). This may give you a butt larger than 8.5 pounds. I find the two separate cuts cook at different rates. The picnic cut; the meat is leaner and has less tough connective tissue, so it will cook faster. You can still cook them to the same internal temperature, if you desire. If I get one with the skin is still attached I will remove the skin and remove the extra fat - trimming it down to about 1/8-inch. If you leave the skin on, your are looking at additional cooking time. The skin and fat releases a lot of moisture; which will keep your cabinet temperature down. Also I would place the butt cut on the lower rack.
As Orion stated, it will take additional time for the cabinet to get up to your set temperature, but how much extra time I couldn't guesstimate. Once the cabinet is at your set temperature it will not take any longer than a 8.5 butt, or the weight of the butt once you separate the picnic end. When I smoke/roast a single 8 - 9 pound butt it will take about 20 hours, and I have a dual element mod, but again your additional will time come from how long it takes your Bradley to get up to your set temperature.
