When you scale up like this, you just gotta be careful of 2 things - amount of liquid and amount of chili spices. I scaled up most of my not-so-spicy spices (chili powder, cumin, paprika, etc.) proportionally, and had a second chili powder mix with my hot boys (Cayenne, Scorpion, Klinger's FL Grove, Ghost, Serrano, etc.) and used like 50% the scaled up quantities to get close to the same heat Salt was added to taste; I doubt that would scale proportionally either.
To control my liquid content, I used beef broth concentrate instead of straight beef broth and added just enough water to get the desired consistency. After walking around, most others looked like chili soup whereas mine had the real chili consistency. I didn't finish in the top 3, but I got rave reviews from everyone that tried it. I'm waiting to get a copy of the final scores to get an idea of how I can improve going forward, though I've heard the judging is very inconsistent. Someone said that if you could turn in a bowl of Hormel chili, you'd probably end up on the podium, so take their scores with a grain of salt. I had a few people who said they sampled all of them, but mine was the only one they came back to for seconds. For me, it was as good as my test batch. There are a couple things I would tweak, but overall, I was very happy with how it turned out.