I sleuthed all afternoon, and learned that American chop suey is basically macaroni, ground beef, tomatoes, sometimes cheese and/or veggies (onions, bell peppers).

So, per 100, buffet style:
20-24 pounds ground beef
12-18 pounds macaroni
2 cups bell pepper
8-15 cups onion
about 20-25 pounds tomato sauce, or some combo of diced tomatoes, tomato puree, tomato soup, etc. sauce (3 cups per pound of pasta)

If you add these items, it becomes Johnny Marzetti:

5-8 cups celery
20 cloves garlic
10 pounds Italian cheese blend
8 pounds cheddar

If you are plating, about 10% less.