I use C-80 in my imperial stout. A mix of 40 and 80 could be just fine. I think your amounts are fine.
I'd ditch some of the MO and replace it with sugar. You could go with brown sugar if you like. I use some in mine. Honey tends to get lost in a beer like this.
As far as flaked, I use some oats and flaked wheat.
I target 1.099 with mine and it finishes in the teens. Quite good and can stand up to oak, bourbon, chocolate, etc.
I think you have plenty of dark grains, but personally I go with chocolate, roast barley, and black.
I've got 10 gallons on the docket for tomorrow. Looking forward to it. 5 will get coffee beans.