The Bigsby isn't for the SG, I'm not a fan of them on SGs (the old Maestro ones look nice though, but only on standards). The lyre tailpiece also looks cool too, but I like the grunt you get with a basic wrapbar on a SG junior. Its all about no-frills with this axe.
The B7 is for my Les Paul standard, it's been my main guitar for the past 18 years (with small spells off here and there, only the odd month mostly). Its crying out for a bit of Neil Young treatment - there a place in the US on ebay that do pre-aged Bigsbys too, so it'll match in with my WELL worn axe.