The caramel malt in a lesser quality might be nice, but maybe 1/2lb is a bit much. You really want to focus on the hop additions and the roasted malts in this style. Lower the caramel, and add in some Carafa II (I used Carafa III successfully in a Black IPA) and Munich malt. I might suggest some roasted barley too. 40+ SRM and 60 to over 90 IBUs. The Chinook looks good, but perhaps increase the late hop additions?
The recipe is good, you're target OG is spot on. You're definitely on the right track.
The Facebook page for Cascadian Dark Ale has an excellent description of the style and lists examples of it. Feel free to check my own recipe out. I've been buying every black IPA i can find and so far i prefer my own over all of them.