i have just fitted some FRS calipers with 324mm discs to an xr2, took a while to make the brackets to adapt fitment, but just have a go with something thin and then get it copied into thicker material.
sadly i'm too poor to do this, so got 10mm steel plate for cheap and spend a couple of hours replicating the 3mm steel model.
all done in a day really, big saving on a kit though.