I just did exactly what you are talking about. We had 150 people show up. I had 80 pounds of brisket, and 85 pounds of pulled pork and we had about 15 pounds of pulled pork to much, but I have to caviat that by saying we let people eat and then make an additional offering to take togo boxes home of the leftover meat.
Without the take home promotion, I bet we could have gotten away with 70 pounds of brisket and 60 pounds of pulled pork (raw numbers). Brisket was way more popular when I did it. If you want more detail on what we did, send me a PM.