I have never used a Meadow Creek, but in my pig roaster I have done 1 169 lb pig, and at a target temp of 250 sometimes with spikes up to 270 I used 90 lbs of charcoal and the cook lasted 14 hours. All cookers are different, so this may not be your times.
My cooker isn't a side burner but an oil tank with a heat diffuser plate. Side burners take more time as the heat is even more indirect.
Humphrey's DownEast Beast W/BBQ Guru