That's my favorite size to cook, but they are hard to find around here. Most grocery stores cut them into 1 - 3 lb chunks and I find that they dry out too easily when cut that small.
I cook mine at 250-ish and they generally take about an hour per pound, but each piece of meat is different so allow plenty of time. You can hold a chuck in a cooler insulated with towels just like a butt or brisket.
