Perry,
You didn't mention the bore size.
I suppose it depends on how you will be hunting. If you are hunting in a large group in the cornfields with retrievers, there can be some long shots. In the past, I'd pick a load and start at 25 yards, moving back 5 yards at a time, shooting at least a few shots, until I began to see the pattern get to the point it's not reliable. I'd pick the maximum range from the patterns and shoot some more there.
If over pointing dogs with a 12ga, modified seems overly tight to me.
