People have done 330mm rotors and falcon calipers before under a 17" rim.
I think in theory your adapter would also work in that setup - s60r rotors and xr6 turbo/xr8 calipers. Caliper itself is the same as normal xr6 but has a longer slide bracket to suit a larger rotor.
Rotor hat offset between s60 and s60r is more or less the same (0.3mm difference). Diameter is 25mm different (330 minus 305).
Only slightly different to the 24mm change in diameter between XR6 and XR6 Turbo (322 minus 298).