Maybe this is a question for Tim and the BKP boys, but I'm assuming these bridges are handmade by BKP themselves. If this is the case are there any custom options?
In particular how about Gibson string spacing? DiMarzio used to make one and they get snapped up very quickly on ebay, I think it's a niche market but one that definitely exists.
Thats a good idea - especially as some strats end up with narrow necks and the strings are dangerously close to the edge of the fretboard
I know we're talking about BKP trems specifically, but some manufacturers already make vintage style trems with narrower spacing. Gotoh do, I think, and the newer Fender Highway One Strats have narrow spacing.
What I'm not sure about is if the mounting screws are still vintage-spaced, or the same spacing as the saddles.
Japanese and Mexican fender bridges have narrower spacing as they are metric rather than imperial. I think it's something like this; USA Fender is about 11.3mm string pitch, Jap/Mex is 10.8mm and Gibson about 10.4mm.