For 35 adults that is WAY more food than you'll need. Especially in the pork department.
I just finished cooking for 40 teachers for a school luncheon tomorrow. I did 2 butts and 4 chickens. That yielded a little over 12 lbs of meat (6lbs each, I weighed the finished product). I always used to plan a 1/4 COOKED weight of meat per person, but the reality is people don't usually take that much. That's like ordering a HALF POUND burger (pre cooked weight).
If it me was my I'd still do the two briskets (because you need more than 1 for sure) but I'd only do 2 butts, 3 if you wanted to have a couple of pounds left over. On the beef, I'd even consider doing 1 packer and 1 flat. While we all know the burnt ends are the bestest fatty most wonderful thing in the world... most people want the sliced flat. Whenever I serve beef the burn ends are almost always the last to go.
Neil -- "Easy Bake Master"
NB Bandera [gone to heaven...conveniently located in Long Island, NY]
Rebel 23, WSM A, WSM B, UDS, Easy Bake Oven
Pork Pistols BBQ
MOINK...It's what's for linner.