How much did that roast way? 1 1/2 hours till an internal of 140 at 210 degrees on the smoker? Well if its a smaller roast, it would not take long. 210 is a good temp and I would go up to 225. Also, you may want to bring your internal temp up a bit, say 150-155 then foil and let it rest a bit. If I remember right, meats that stay in the so called, "danger zone" 40-140 too long run the risk of bacteria multiplying. I don't think its going to be tough at all, should be very tender. I see this is your first post? Take a minute and stop over at roll call and give us an introduction, Name, where you live, hobbies, stuff like that along with any smoking exp you have. Oh yeah, don't forget to take some pics of your smokes and post them, we like to see our fellow members bbq.