7# ground beef- is this precook weight?
7# chicken - is this precook weight?
140 shells- 70 hard and 70 soft
not sure about chips
7# shredded cheese
4 heads of lettuce or 42 oz preshred
21 tomatoes - diced
7 large onions
112 oz of sour cream or 7 16oz containers
7 cups salsa

7# ground beef- is this precook weight? Do 10 raw
7# chicken - is this precook weight? Do 8 raw
140 shells- 70 hard and 70 soft- OK
not sure about chips- 1 pound per 10
7# shredded cheese- too much- 2 1/2 or 3 pounds- you could add 1 can nacho cheese in a crock pot
4 heads of lettuce or 42 oz preshred- OK
21 tomatoes - diced- only 4 1/2 pounds
7 large onions - 2- 2 1/2 pounds
112 oz of sour cream or 7 16oz containers- plenty, probably some left
7 cups salsa- I would go 2- 2 1/2 quarts

I would have either beans or refried beans for the non meat eaters and to reduce the meat: 1 gallon or about 8 pounds

a quart of jalapeno slices and chooped cilantro would be very nice.