Lactose to a Chocolate Stout?

[Stigy]

I found this recipe for a nice mint chocolate stout on these forums and scaled it down to 2.5 gallons (recipe and link below). One of my friends who has been brewing for a while recommended I added lactose in a ratio of 2:1 (6 ounces below) to compensate for my unsweetened cocoa powder?

What are your thoughts on this as opposed to using sweetened cocoa powder? I have read up on it and see its an unfermentable sugar so you get the sweetness of the sugar as well.

Your thoughts are greatly appreciated.

Recipe Specs
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Estimated OG: 1.054
Estimated FG: 1.013
Estimated Color: 25 SRM
Estimated IBU: 37 IBU
Boil Time: 60 minutes

Ingredient List
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4 lbs - 2 Row UK
4 oz - Carafa 3
4 oz - Crystal 40L
4 oz - Chocolate Malt
8 oz - Flaked Barley

1 oz - East Kent Holdings @ 60min

3 oz - Unsweetened Cocoa Powder @ 5min
5 Peppermint Tea Bags @ 10 min

Original Recipe: https://www.homebrewtalk.com/f68/all-grain-andes-mint-chocolate-stout-207277/