Newf,
It looks like you are going to do the ground breaking work on this project.All kidding aside,most of us on the internet are too young(even at 69)to have any experience with loads like you need.You might find what you need in really old shotgun loading manuals(now hard to find)or old bullet mold manual(if they offered round ball molds).You should be able to safely use the same powder load with round ball, that you would with shotload of the same weight.Failing this, the powder manufacturer may provide information.
Mike
