A week or so spent pulling bits off the bike has resulted in this.

The next stage would be to remove the engine from the frame but until I can remove that header pipe that'll have to wait.
There's a castellated nut made from relatively soft bronze holding the header pipe to the cylinder head and it wont move, even with a specialist spanner bought specifically for this job. I've just tried Plusgas penetrating fluid on it and will persevere for a bit but if it doesn't look like there's any progress there then it may have to be partly destroyed to get it off.
I've found a firm in Italy that sells new ones at about £40 for a pair.

I'm still trying to work out which version of the wiring I have, not helped by it all being so coated in grime that most of the wires are just shades of black. A bit of cleaning there may make it clearer.
At least some of the components like the coils and reg/rec box look new, so someone has rewired part of it in the near past.

I've decided that after I get the existing powdercoat removed from the frame I wont be redoing it, I think paint will give me a nicer finish,if not as durable. I may or may not do this myself. I think it ought to be black too.
The wheels will definitely need repainted, I'll probably get them done in a paint shop. 'Skoda Donington grey' is the paint colour that matches the original colour so I'm told.

The engine number appeared out of the muck on the back of the crankcase, apparently put there by the importer as the factory didn't bother to stamp them and it's a legal requirement in the UK.

The tape around the headlight was holding it together as I suspected, however it wasn't as bad as it could have been, the only things missing were two small nuts and bolts. I cobbled some together for the moment and will fix it properly in due course.