Make it occurring before the Quincy Wars. You can remove a bunch of the characters (you'd have to keep some of the lesser known, meaning the DM has more freedom). Alternatively, a crossing of countries after life settings like Midnight suggested sounds fairly sick (if it does mean that the Spanish all turn into demonic hollow thingies... but then again it explains luchadores.... wait, hollow masks-HOLYSHIT!
Zanpakuto (I've been thinking about it since my Let's Go Ultra Hero Super Burning Dimension Force, LGUHSBDF for short, character is a shinigami rip that I've decided is actually really poorly executed... meeeh...) are legacy weapons; I've been trying to think of how to stat out each one. Fox-headed guy's Bankai (17+ lv Legacy ability)? Summon Monster some giant mo' fo'. The Healing captain's shikai? Phantom Steed ability. Etc, etc, etc.
I'd love to try helping stat out characters for this game, as long as everyone understands that there is no way anything going on in the most current manga is anything close to pre-17th level stuff.
Plus, I'd love to have a swing at making a new shinigami! So yeah, I can definitely help with construction, though I can't run it for shit.