By way of an update, I've gone with the following:
Front: 18" x 7.5", ET23. Tyres will likely be 215/40/18
Rear: 18" x 8.5", ET12. Tyres to be 245/35/18
The wheels are on order from Work in Japan with a lead time of 6-8 months, so I'll resurrect this thread once they're received and fitted so anyone from the future who's interested can see how I went.
