Superbrights are actually hexcore - they just use a smaller core which makes them more flexible.
Black Label Dunlops sound different to Superbrights - they're more broken in from the start and not as bright. If you want a similar feel to 45-105 SS Superbrights, I would go for 40-100 personally. 45-105 would be more tension for sure, perhaps too much? The Black Labels are very similar tension to XLs and Slinkys in my experience.
DR Pure Blues and SIT Foundations are two other strings very similar to Superbrights. Pure Blues are probably the stiffest of those three.