Need to cook pasta for 200 people
To really get an answer you should definitely do a test dish. Prepare 1 or 2 portions as you usually do at home. If you approve the result just multiple the  ingredient quantity. To me it is impossible to give you a better answer as your portioning has to depend on how filling the sauce is as well. Also doing a test of the recipe will be helpful for your peace of mind on the big day.
Hope this helps :)