Ribs and Brisket for 50

I am cooking up ribs and brisket for a party I'm having . So far I have roughly 50 people coming, mainly adults. I was planning on cooking 9 rack of spares, cutting them down to St Louis cut and serving the ribs and rib tips. I was also going to cook a couple 13lb briskets as well. Along with the meat I anticipated on making 3 half pans of Mac n Cheese, 3 half pans of slaw, 2 half pans of smoked beans, as well as enough corn bread for everyone.

Since I have never cooked for this many people, does this amount of food sound like too much, or too little?

I appreciate the help.

I know this is a little late, but figured I would post the outcome of the party I cooked for. Bottom line, I didn't cook enough food. We ended up making 9 racks of St Louis cut spare ribs, the rib tips from the spares, 2 - 15 to 16lb briskets, 4 half pans of mac n cheese, 3 half pans of slaw, 2 half pans of beans, and 60 corn muffins. all of it gone!

When I asked my buddy who would be attending the party, he said about 50 average sized guys. The party was for another friend of his who owns a cigar shop. Anyways, to me that sounds like roughly 50 people, with a avg weight of 150 to 200lbs. Well that was way off. There were roughly 30 people that showed up, with an average size of 6' 4", and roughly 3 bills. All these guys had to have been ex NFL players. The food lasted roughly 90 minutes. But that was ok, cuz everyone had there fill, and no one was left wanting. Each of them had 2 or 3 plates, and ate like someone was going to take it away from them. If I hadn't seen the size of these guys, I would have assumed they had fasted for a week before showing up.

So the take away from all this, next time I am going to ask what they think "average size" is, cuz obviously we each have our own definition. All in all it was a success, and received numerous compliments about the food. Thanks for all of the help.