I think it'll make beer!
That said, most brewers agree to use pale/light extract vs. darker types. Malt extracts should replace only pale/pilsner malt.
Amber and dark extracts already contain a proportion of Crystal and roasted malts to provide color and flavor. Briess dark extract, for example, contains pale, Munich, crystal and black malts in the extract. If you use amber or dark extracts you lose a significant proportion of the control you have over the finished brew. Thus, I'd cut the Dark LME and replace it with 7 lbs pale/light LME.
I also think you've got way too many and too much specialty grains. Let's take this one at a time.
The primary specialty grain - the ingredient that makes Stout Stout - is Roasted Barley. A full pound is good for five US gallons.
A full pound of 120L Crystal is overwhelming; I'd not exceed a 3/4 lbs of Crystal of any type, and I'd make it a lighter Lovibond. If you want a broader spectrum of Crystal/caramel malt flavor, try a half-pound of 40L or 60L and a quarter-pound of 80-120L.
CaraPils is not necessary. If you use Briess extract, even the palest extracts already contain a proportion of it, and you're adding more crystal malt. Roasted malts enhance foam retention. Thus are both enhancements provided by CaraPils covered elsewhere.
Chocolate malt isn't necessary, especially alongside Roasted Barley. Some brewers prefer a broader spectrum to roasted-malt flavors in their stout; I disagree. If I can't immediately identify the roasted grain as Roasted Barley, I get confused.
Brown Malt must be mashed. It can be steeped, but it doesn't add much. Moreover, the little it does
add will be entirely overwhelmed by the other roasted grains.
Now let's look at the hops.
I don't think finishing hops are particularly useful in Stout. I find hops flavors cloud the flavor-spectrum of the roasted grains. I'd especially not waste East Kent Goldings - my favoritest hops EVAR - in that role. Save 'em for your Bitter and English Pale Ale.
A 1:1 BU:GU ratio is a good one for Stout. Stout should be intensely bitter. But don't forget that much bitterness also comes from the Roasted Barley. So adjust your hops accordingly.
Let's rewrite that recipe now.
7 lbs Pale/Light LME (late addition)
1 lb Roasted Barley
8 oz 40L Crystal malt
4 oz 120L " "
1 oz Nugget @ 13% AA - 60
That should give you:
IBU: 50 (assuming full boil)
Hope this helps!