Stan,
All said and done...and as others have alluded, given all the variables of ammunition, forcing cones, choke cones and whatever else I didn't think of, I think empirical exploration (pattern testing) along with a rough SWAG, is going to accomplish what you want in a much more expedient manner and with greater accuracy. From that data, you could build a chart.

I've had some 3/4 oz and 11/16 oz .410 loads that had great pattern distributions and some that didn't in various guns for various reasons, most of which I never figured out, but only speculated. As I'm sure you're aware, the .410 is a fairly fickle firearm. I love 'em.