I know people slate it, but ebay can be damn handy sometimes.
Brand new Goldspeed 320mm rotor to fit my XR front wheel for just under £50 all the way from Portugul.
Now that's mint in my book. I now need to punt on the original 320mm disc I got for the NX 650 front, it'll fit an XR 650L as well so it I should be able to find a buyer on said same auction site.
With a bit of luck next week I should be able to get this fitted up and measure up for the caliper bracket so I can order all the material I need for that and the rear disc spacer, and possibly a fork brace which should look good and be functional, as well as giving me somewhere to bolt the part time front mudguard.