I think you in the ballpark with your 5 oz servings.... I also think you need somewhere about 85-90 pounds of cooked meat to serve...I'm also thinking if you have 180 pounds of uncooked meat, you will, plenty of leftovers.... I dont see you loosing 50% of your total to a cook... an 8 pound butt coming out the smoker, only weighing 4 pounds????....not on my smoker... I usually count for an avg of 35% shrinkage