For anyone interested, I ended up ordering a Seka Exceed RDC and it’ll get some parts off another bike. Seems to be an 8 week turnaround.
Shall provide feedback for anyone interested, but basically my reason for going this route is that I wanted: (i) an aero frameset that wasn’t a boat anchor (no real use case for “full aero” in Japan as it’s too mountainous); (ii) threaded BB (this is T47); and (iii) clearance for 700 x 30 or over (there’s some races with some gravel here that better suit wider clearance).
Originally I’d wanted an SL7 or perhaps an Ostro, but both are mental prices and shite availability at present. Time will tell, but this doesn’t seem to be too far from those framesets.