Well I finished the custom adapters and got the 256mm girlings fitted. Test fitted my 13x6 revos too (unsure of offset) and it seems they will clear with about 25mm of spacers. So any one wondering, it is possible.

I didnt actually bolt them on, as the bolt spacing is weird. The spacing seems to be 4 1/4". Any ideas?

thats interesting!

but as i previously said, if you want to spend money on a proper brake upgrade, the WMS calipers would have fit with roughly the same amount of spacing! :)

Yeah, but these 256's are cheaper!