Marcel Thys has retired recently and closed his business. He was certainly among the finest builders of double rifles ever. If the rifle is in good shape, by all means buy it. There will never be any more - Thys' sons are not interested in the business from all accounts.

Fitting a scope on a double would be like putting a roof rack on a Ferrari - a statement by someone who has several double rifles by Trevor Proctor.

That said, if it's your Ferrari, you have every right to have a roof rack if you want one. It is no one else's business what you do with your rifle, though, a mint Thys may lose it's value with modifications if you plan on selling the rifle at a later date.

Do post pictures of the gun here if you buy it.

Cheers!