These are great plans you have here Eyal,
I'm sorry you can't get married in Paris, but Italy is also great.
As it comes to find some vintage Heuer in Paris,
this is unfortunately not the best place.
Paris will always be Paris but will never be Munich...
Tag Heuer just opened a shop in St Germain Des Prés,
so if you'd prefer a 300SLR, you should be able to make it.
I'll be able to check if there's a watches fair while you'll stay in Paris and will ask around me for Heuer availability with dealers.
Feel free to drop me an email, I'll be happy to help if I can.
cheers, Laurent from Paris