Importing car collection to France

Hi, any informed advice would be gratefully received. I have a small car collection in the UK- fairly normal cars, but all over 30 years old. The cars are permanently stored and all on UK plates and SORN here and are never used on public roads. They do not have MOTs either, just because they are not used on the road. I want to move to France and get them exported to France via a transporter. If the cars are not used on roads in France in future and are effectively stored at my new home in France do I have to re-register them on French plates? Also, do they have to be taxed and insured if they are in storage? Not being familiar with the French system I don't know if they have different requirements.