Quick update.
I've managed to squeeze a CB350 twin leading shoe brake in there. The rim needs to be offset to get it in the middle.
And the lug didn't match up so my friendly machinist made a plate to match them up.
The swinging arm seems too wide. It has a 9.5 mm gap each side when the wheel is centred. I guess I'll have to get some spacers made up, or have I missed a couple of parts? That's how it came apart, the swinging arm was squeezed up tight when the axle was done up. It's a surprise it hadn't distorted.
Did I mention the top fork yoke? There are a couple on ebay that I may bid on.
I got a bit disheartened by all the hassles so I decided to cheer myself up by getting the spray cans out to make it pretty.