Seasoned taco ground beef = 20 lbs
Seasoned taco shredded chicken = 20 lb
Flour tortillas (No hard shell tacos) = 200
Refried beans (Covered in Mozzarella cheese) = 15 15oz cans
Mexican Rice = 2 chafer pans full
Shredded Lettuce = 10 lbs
Shredded Mexican Cheese = 15 lbs
Sour Cream = 8 lbs
1 gallon chopped tomatoes
1 gallon salsa
2 16 oz sliced black olives
4 8 oz jars jalepeno peppers
2 lbs chopped onions

5 gallons sweet tea
3 gallons unsweet tea
3 gallons water

Flour tortillas (No hard shell tacos) = 200- OK, but people do like corn tortillas also
Refried beans (Covered in Mozzarella cheese) = 15 15oz cans[ OK
Mexican Rice = 2 chafer pans - you want 60 cups- not sure how big your pans are
Shredded Lettuce = 10 lbs- plenty
Shredded Mexican Cheese = 15 lbs-8-10 plenty
Sour Cream = 8 lbs- OK
1 gallon chopped tomatoes- plenty, 3 quarts likely sufficient
1 gallon salsa- plenty
2 16 oz sliced black olives- at least 2 quarts
4 8 oz jars jalapeno peppers
2 lbs chopped onions

A couple of bottles of Ranch dressing and 4 pounds of corn chips would expand the possibilities to taco salad. Fruit trays are a great addition to the taco menu.