That is one complicated grain bill! The 1.5 lbs of chocolate malt seems like a lot to me and I think you would want to use some roasted barley, also. You may want to have some roast-y flavors to help balance the lactose and chocolate, perhaps.
For what its worth, I use around a half lb of both chocolate malt and roasted barley in my basic sweet stout recipe - its not a chocolate stout, though. If you want to look at the recipe, its here sweet-stout
Adding the chocolate at bottling sound interesting. I've never done that with chocolate, but have with herbs, in a tincture or potion with vodka. This should be an interesting experiment!