Beautiful safe Craig, if you search google for “Bauche coffre fort ancien”, and select images, you’ll see countless similar safes to give you an idea of what you are up against, there are some mechanism shots about too.
There are loads of variations on them, but they nearly always have the key operated latch action in addition to the main bolt work. If you are incredibly lucky in the unlikely event that it’s only locked on the latch, it can be opened relatively easily with a single strategic hole, which can then be plugged to repair.
If it’s not, and it’s fully locked on everything then it’s not really one for the inexperienced to practise on, you’ll end up doing major damage and that’d be a great shame on such a beautiful antique- it would also defeat the object of restoring it!