Thanks, guys!
I was actually amazed by how much reference for the Big Chap head I was able to find online, but in doing so I discovered that there were about 5 different heads made for the movie, and each one was painted a little differently. The overall head shapes and proportions are also slightly different. It was a challenge to figure out how to incorporate the overall look of different heads into one piece that had everything I wanted to see in my own personal holy grail Big Chap.