When I looked into this I found you could get 310mm disks to fit with the standard calipers & original wheels. Thats a big leap over standard & it doesn't look to dissimilar to the original setup, my plan was to fit this lot:

310mm Grooved disks.
Braided hoses, full car set.
SRF fluid.
New calipers Preferably or recon.
DS2500 pads.

job done.