Well I started this afternoon.....
It's actually easier than I hoped...

Only need to widen the caliper hanger by about 1mm as it fits atm with a little tap from a hammer so once its had a 1mm trim it'll be a nice fit

Then its just a case of making the brackets which is also easier than I'd hoped

2 small plates (1 for each side) of steel 140mm long, 60mm wide and 6 mm thick and 4 holes drilled 10.5mm and it's all done and just needs bolting together.
Steve