I don't have a lot of experience with recipe design, but I can provide some links.
Check out this excellent 2010 article from Brew Your Own magazine on Black IPAs. It says that the Great American Beer Festival adopted that style as "American-Style India Black Ale", and the characteristics are:
- Color = 25+ SRM
- Original Gravity = 1.056–1.075
- Final Gravity = 1.012–1.018
- Bitterness = 50–70 IBU
- Alcohol by volume = 6–7.5%
BYO seems to suggest you should replace your black malt and roast barley with debittered black malt. I also found this this blogger's article on a hypothetical splitting of the pale ale styles, including his/her interpretation of a new black IPA category.
The BJCP has not added a Black IPA category yet, AFAIK, but can cehckcheck out the BJCP Style Guidelines for Russian Imperial Stouts (Category 13.F.) to make sure you arearen't straying too far into that area. Seems like there is some overlap between the GABF's black IPA description and BJCP's RIS, and you are in the intersection in terms of metrics. But at the end of the day, what difference does it make how the beer would be categorized if you achieve the flavor and other characteristics that you desire?
Personally, as a fan of Black IPAs, I differentiate black IPA from RIS by prominent American aroma and flavor hops (citrus/pine notes), roasty and coffee flavors being muted despite the darkness, and no alcohol heat or vinous character. Maybe look to commercial examples for inspiration - my own models would be 21st Amendment's Back in Black (first one I had, so it defines the style for me), New Glarus' Blacktop, and Lakefront's IBA.
Isn't it nice to be able to brew what you want and have fun?