Adding Cocoa to BB Milk Stout

I am brewing the brewers best milk stout recipe kit this weekend. I really want to beef up the chocolate flavor by adding cocoa powder. I have researched it here on the forum and am thinking I will use 8 ounces of cocoa powder to the boil at 10 minutes. Thye recpie calls for .5 lbs of lactose and .5 lbs Maltodextrin. Does this sound correct? any comments are appreciated. Here is the recpie as I have it

Chocolate cream stout
Style: Sweet Stout OG: 1.053
Type: Extract FG: 1.013
Rating: 0.0 ABV: 5.24 %
Calories: 173 IBU's: 23.89
Efficiency: 80 % Boil Size: 4.00 Gal
Color: 25.5 SRM Batch Size: 5.00 Gal
Preboil OG: 1.070 Boil Time: 60 minutes
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Fermentation Steps
Name Days / Temp
Primary 10 days @ 70.0°F

Grains & Adjuncts
Amount Percentage Name Time Gravity
0.50 lbs 6.17 % Lactose 60 mins 1.030
8.00 ozs 6.17 % Caramel/Crystal Malt -120L 60 mins 1.033
4.00 ozs 3.09 % Roasted Barley 60 mins 1.025
4.00 ozs 3.09 % Chocolate Malt 60 mins 1.028
3.30 lbs 40.74 % Dark Liquid Extract 60 mins 1.036
3.30 lbs 40.74 % Munton's Light LME 60 mins 1.037

Hops
Amount IBU's Name Time AA %
0.50 ozs 20.22 Magnum 60 mins 14.00
0.50 ozs 3.67 Cluster 10 mins 7.00

Yeasts
Amount Name Laboratory / ID
1.00 pkg Nottingham Danstar

Additions
Amount Name Time Stage
0.50 lb Malto-Dextrine 60 mins Boil
8.00 oz Chocolate 60 mins Boil