Anyway, I then decided to take some resistance readings from the alternator connectors. They were as follows...
White-Blue = 5.2 Ohms
Green-White = 336 Ohms
Green-L/Blue = 138 Ohms
Green-Pink = 14.9 Ohms
White-Earth = 338 Ohms
So they all seem within range. The surprise came when I took a voltage reading from the white and blue connectors with the engine running - both were around 30odd volts instead of the 90-100v.
Just as I sat there shaking my head, the carb overflow pipes started dripping petrol onto the floor
I then spent time replacing the Nippondenso CDI for another one, but it made no difference. I checked all the connectors in the ignition circuit, cleaned them with switch-cleaner, checked earths, etc, etc, etc.
What now? I think I'll put the original stator back in for a start, because that looked like brand new and all resistance reading are perfect. The carbs will obviously have to come off again to cure that damned float-valve leak too. After that, I think I'll commit hari-kari!