Here's the finished bracket looking a bit sexier. Some time on the mill has cleaned it up and removed a lot of excess material that didn't really add any extra strength.
Here's the disc and caliper in place. I'll probably slot these discs to match the front. DBA didn't bring out the slotted versions till after I'd bought these
One of the things that can be a problem with fitting aftermarket discs to these rear ends is there isn't much clearance between the disk and the wheel hub. The calipers I ordered are the low profile version so I gained about 1/4" over the regular version. I also spent a fair bit of time working out how deep the boss needed to be on the back of the wheel and where clearance could be gained. Peter at Ozwheel did a great job finding clearance with the numbers I gave him. He couldn't make the wheel boss any deeper because of the pin drive hubs. He machined the backs of the spokes to gain the extra I needed. There's about 3 or 4mm clearance between the caliper and the spoke which is plenty.
Cheers