Chuck roasts are excellent for pulled beef. The meat will take as much time as it needs to break down the connective tissue and will normally have a long plateau around 170*-190*. I use a probe thermometer for doneness and take the roast out when it reaches 205* internal. I then let it rest for an hour or longer. Sometimes foiled on the counter, sometimes foiled in a cooler. (If I am going to let it rest longer) The meat comes out juicy and is very easy to pull. I do the same with Boston Butt, but it comes out with an internal of 195*.