Well their quart size bags might work but they would be tight and the gallon size are a little big for that amount..if it was me I would go for the gallon size or as TK said you can buy the roll and make your own size bag which in the end is the most economical thing to do. Which is also what I do, I quit buying individual bags some time ago.
Treasurer, Great Lakes BBQAssociation
Rubbed, Smoked, and Sauced Competition BBQ Team-
22 1/2" WSM, 2 18 1/2" WSM's, 22 1/2" Weber Kettle