[Hanuman]

The original WR brakes setup used a 280x22mm disc. Single piston caliper- G54 I think. The G60 caliper and thicker disc came in on the MB, but I've seen quite a few WRs with them too.

On the track, with the original setup, I'd be getting fade, using green stuff pads, then later red stuff.
I wanted to uprate. I went the G60 route which is a similar design caliper, but 2 pistons, and a thicker disc.
You would need 2 calipers, 2 carriers, 2 discs, set of pads. It's a straight swap, mechanically. Pete Reeve may even still have a source of the caliper carriers.
However- If I remember correctly, there is a length difference in the hydraulic hoses. Using Goodridge braided hoses, one version of the hoses being at the end of their free length on full steering lock. I just can't remember exactly which combo.

There was a much greater improvement going from single piston to twin piston calipers, than going from twin piston to Porsche monoblocks.

If that makes sense.