Lots of good advice so far. Only thing I can add is that if you plan on smokin it all the way thru the cook (and not panning w/liquid) be sure to look for one with some nice marbling throughout. It'll make for a more moist and tender roast. You're gonna love it either way though, smoked chuckies are great!
UDS'-55&16, Akorn, Bar-B-Q Kettle, Drum Grill, miniWSM, cobweb-covered gasser. I'm JD.