At the moment, the worst case is to drill & retap the original calipers in the next size up & reuse the bolts I'm now using to hold on the ST205 calipers (ie 14x1.5, original are 12x1.25), then drill out the tapped thread on my hubs.
This does mean that I won't be able to reattach the 205 calipers to my car (something I'd like avoid doing at this stage).

Currently organising to ship da_horse's ST215 Caldina front hubs up to see if they'll fit (for some reason, the 4WD front hubs are different to the FWD, still can't figure out why )