If you are intersted, I will go down to my local TSW outlet and ask them if they still have some of the correct centre caps and wheel nuts for those rims. While there, I will try and find the correct name for these wheels.
The centre caps were small plastic ones and were not expensive to buy.
The correct wheel nut was a big 24mm chromed nut with a step down to a much narrower shoulder (about 17 - 19 mm) that fits into the mag wheel. It also comes with a big washer. They are not that expensive, but when you have to buy 16 of them, it does get a bit expensive (in ZAR terms). The weight may also make it expensive to post them from SA to France. They also came in left hand thread, but I doubt if any of these are still available. I may still have some of these wheelnuts at home, and if so, will take a picture and post it here for you.
I used to race my brown Berlina with various Tiger aliminium wheels, so I know their products very well.
I will look around to see if I can get some pictures of my Berlina with the wheels visible and post it for you. Unfortunately I no longer have that car.
I have a sister-in-law who lives in Paris and I can always try and send the correct bits along to Paris with a family member when they go there to visit. It should be a lot easier for you to get things from Paris, than trying to get it from Johannesburg.
Malcolm