One thing to think about as you are considering your new pond level is that it will not always be at full pool. I have ended up raising 5 of my ponds level by at least a few inches (nothing major like you will be doing).
When you are designing the new full pool level and envision the new banks and perhaps a dock or other features, a person tends to see it at full pool level. But with a watershed pond in the midwest reality is it will only be at actual full pool maybe 10 or 20% of the time. For short times it will be above full pool while water is exiting the overflow, but for a cconsiderable part of the year it will be an inch to perhaps a foot below full pool during dry periods.
So in your "vision" of what the new pond will look like after finished, consider also what it will look like at 6" below full pool. With adequately sloped sides it may not look much different. But with lots of shallow water almost flat banks it can look quite a bit different.
