We are bbqing for our church 120 people, They would like Santa Maria style BBQ smoked over Red Oak. We will be using untrimmed Tri Tip roasts & Whole chickens cut in half.
My rule of thumb for how much meat, assuming there will be side dishes to go with it, is 1/2 lb. of meat per person in which case you would need a total of 60 lb. of meat. When you say you are cutting the chickens in half…will you be carving the meat off of each chicken or are you planning to serve, a half chicken, to each person. If that be the case and at least half of the people eat chicken…you will need to purchase at least 30 chickens. For the tri tip, if you want to make the servings larger for it…I would then go with 3/4 lb. per person, assuming half of the people would choose to eat tri tip…then you would need 45 lb. of tri tip.