A few simple parts bolted back in place and it looks like I've made huge strides in rebuilding this bike.
It now has its face back, at least for now, I suspect I'll need to take some of it back off to check the wiring when I can.
The bars are new, the old set, while perfectly servicable came off something else and the knurled sections didn't match the clamps so I bought these ones, they are pattern ones for a old BSA -A, B and M models, they are slightly pulled back than the other ones but look fine.

The wiring is getting complicated now as I try and figure out what connects where, I think this will be the hardest part to get right.

Still here

This was that brake disc posted previously, left in a bath of.....tesco cola for two days it cleaned up quite well.
I'll paint the carrier part with HT paint (though the first attempt looks very splotchy) before bolting onto the wheel.
I've decided that I'll shave 2mm off the lower mount of the caliper and use a thinner spacer for the top mount to compensate for the difference in offset of this disc compared to the original one.

Both carbs are now cleaned, a new set of bars will be here shortly. Mudguards have been stripped of paint and I need to decide how to finish them.
Footpegs are sprayed a satin black and ready to fit so though nothing has progressed much I've done afew things at least.