Despite being told NUP, I went ahead and bought the headlights for the Cobra from the states, got them at a great price too, landed on my door step, $140.00 for the pair. On checking them against the old ones, they are identical except the new ones have smoked lenses. Fitted them yesterday and they work exactly as the old ones did, dip correctly. Made a great differance to the car also. Seems some things just work out for the best.
I had tried the polishing thing with some success but they still didn't look the best.