Thank you for the PDF that is the first one I have actually seen that is the same look as the engine I am working on and does confirm that all the parts are in the correct place.
I gave it a pull with the plug cap removed but got no spark. Took points out and gave a good clean, put back in set to 18 thou, which is also written on the inspection cover. Took out the coil to take a picture of the back as this is where it looks potentially damaged. When I took the coil out the HT lead fell out so was not connected properly, secured this and put everything back together. Went to tighten crankshaft nut and bang snapped the thread, on inspection it did have a rust line into it so I looks like it has been weak all through my testing I have just been lucky until now. I have uploaded the pics of the back of the coil.
I have not given up with this engine I am just going to try and source a replacement crankshaft before I can try and get to the bottom of no spark. Or another engine and I can swap parts around as required.
Thanks for your help this far