What kind of bulbes is in the Murena headlights? (H3, H4?) Mine are working perfectly but I am keen to replace the bulbs with yellow ones to give the car the right "french" look.
The head lamp bulb should be a standard Quartz-Halogen H4. You can get a yellow version of this, but all it is, is a yellow envelope around the standard quartz one... and they are more expensive.
A yellow paint was used on the Tungsten-Glass bulbs in the past, in France particularly, to reduce glare from lamps that were not so well defined as today and therefore the beams could dazzle sometimes. Simply by dimming the light output (the effect of the yellow covering of the glass) they reduced the possibility of that glare BUT it also meant you had worse vision in the dark!
We now have accurately defined beam patterns, so provided the lamps are properly aimed, you get better vision in the dark and no dazzle. There is no need for this yellow covering. This is why the French cars no longer have it. After all the manufacturers have spent lots of time improving the light output to allow you to see better, you want to artificially reduce it again!
As for originality, many French Murena did NOT have yellow lamps fitted from new, just like other modern cars. I think they only had them on the very early batch. I know certainly many 82 and 83 cars, such as yours, that I saw new had normal white lamps.
So if you want to spend more just for appearance, consider you are paying more to see less. I hope you don't drive much on unlit country roads at night. :-)
Roy