I have a couple 7's that I made around here and since I don't play them extensively, I'm kind of rusty as to how to explain this exactly. But string gauge is only part of the equation, the other part is the ratio of core to winding. I can't remember which is which, but I believe that a larger core with a smaller wind is better for the B. It will carry more tension and produce a stronger tone. A skinnier core with fatter winds will be sloppier. Now, I can't tell you for the life of me what brands do what, but some brands list the core size. If you go too heavy with the string gauge and the windings are too thick comparatively, they can choke off the notes. Anyway, that's my two cents.
I also have Bartolini's in both, and that, to me, is essential if you want the ultimate in clarity and string separation. They are unsurpassed.