Silly question,

Could you use Rover MG discs get the PCD changed and just relocate the caliper?

They are showing:
Dia: 325mm
Height: 35.1mm
Thickness: 25mm
Centre Bore: 64.2mm

Compared to the Cossie:
Dia: 278mm
Height: 35.2mm
Thickness: 24mm
Centre Bore: 63.7mm