Stan - have you checked out the pattern programs that Dr. AC Jones has posted on his website -
Shotgun Insight The Pattern Optimizer and Pattern Simulator can provide some useful visual information of pattern densities from different loads, along with some interesting statistical analysis of what pattern densities are required to ensure a certain likelihood of pellet strikes. While it is "hypothetical" in the sense that the patterns are randomly generated by a computer program and not actual shotgun patterns, they still help provide a visual sense what an 70% pattern of #8s looks like compared to a 80% pattern of #7 1/2s, for instance. It takes a little tinkering to figure out, but I found it worth the time.
