Both pics are beautiful!
I have done exactly this before. I must warn you that if you put black dye over that porous bleached hair it is going to be BLACK - like unnatural gothic black. I would go with dark brown because that would probably come out closer to the "black" you want. Like mine right?
Also - be mentally prepared for the color change - going from light directly to dark can be a shock to you. You may want to do it gradually in case you change your mind. Even then - if you decide you want to go back - it's probably not a good idea.