I would say 20 pounds of each finished product. That will give you 60 sandwhiches each. You will have some left over. If you want to cut it close do 15 pounds finished of each.
I just served Pulled pork and chopped chicken to a wedding party of 250. We had very few people go through the line twice, we had an equal number eat big as ate small. The crowd served themselves, and we refilled chafers. The crowd ate an equal amount of pork and chicken. We served out about 35 pounds of each, as well as sides of cheese potatoes and baked beans. The wedding party provided cheese, chips, dip, and a handful of side salads.
We had wonderful reviews and picked up a client who just booked us for 200 people the 6th of April.