Some items a short for 275 if it is a self service buffet. Here are my suggestions.
• Tortilla chips (24 lbs)- OK, none left
o 2 gallons salsa- 4 1/2 - otherwise you have less than 2 tablespoons per person
o 2 gallons guacamole- at least 4 1/2, people tend to get piggy on this
• Veggie Tray
o 12 lb cauliflower
o 20 lb bell pepper slices
o 12 quarts grape tomatoes
o 12 lb carrot sticks
o 24 cucumbers, sliced
o 12 lb celery
o 12 lb pea pods
Veggies are almost double what I would expect- usually, 1 pound per 5 is plenty, and the bell pepper is probably double in proportion
o 12 cups dip
need about 4 gallons
• Relish Tray
o 12 lb black olives
o 12 lb green olives
o 12 lb pepperoncini
o 12 lb tiny dill pickles
o 12 lb tiny sweet pickles
OK, but suggest you add same amount something like marinated green beans or artichoke hearts?
• Cornbread (20 9X13 pans)- not enough. Only OK if you add at least 10 pounds of crackers, or 8 more pans
• Chili (24 gallons)
• Vegetarian Chili (6 gallons)
Good split, but probably about 1/3 too much, unless they are enormous eaters
• Sour cream (20 lb)- OK
• Cheese, shredded (15 lb)- shy, at least 3 more pounds
• Hot Sauce - 12-16 bottles
-- you need about 14 pounds chopped onions
• Potato salad (80 lbs)- this is about 8 gallons, I usually do about 12 for this size group
• Coleslaw (80 lbs) - OK