Snow,
Maybe not quite what you're looking for but Morgans Master blend chocolate malt contains 15% Chocolate Malt Grain and 85% Munich Malt Grain being 200g Chocolate grain and 1150g Munich - & their Master Blend Roasted Black Malt contains 12% Roasted Black Malt grain and 88% Munich being, 160g Roasted and 1190g of Munich grain. Could help when the additional dark malt doesn't put your recipe out of spec...