I used a 9Round-Shader to fill in the black areas; two passes with the needle, could have gotten an opaque black if I did a couple more passes, but I wanted a more weathered look to it, given the post-apocalyptic vibe I was going for. Definitely a lot faster and more uniform than trying to pack black/color with a lining needle.
I used Kokkai Sumi ink instead of the “Infinitii: Black Outline” that I like; so far I like the Kokkai Sumi, but I don’t have any done with this ink that are fully healed yet, so I can’t give a firm opinion as of yet.