Seeing as you were asking about cases, I'd be looking at 3 + cases of Boston Butts, I'd actually look at 4 and use 50% yield not the 55% I'd normally use, as the more tired I get the more persnickety I get, the more clean I make the pork. (Strange I'll admit)!
So cases are weighing in around the 80 lbs mark and you need 250 /bs uncooked, so you could get away with 3, but as a paying gig, I'd be with the other guys about the price / lb, though round here it's between $9.00 and $11.00 / lb.
The beef gets a higher yield and you could get away with the 3 cases 80 lb / case of chucks.
"There is no such thing as a little garlic." A.Baer