I don't know how hard it is to find a vintage Mopar in Austria; is it hard? 4000 euros comes to over $6000 Canadian dollars. You have to factor in the difficulty in finding a vintage Mopar in Austria and what it might cost to ship one there, so maybe it's actually a good deal for you, but to me it seems a little high priced.
BUT...if it's a real 340 S car that adds value too. Only you can decide. It looks like it has great potential to get a great car though, that's worth all the money right there!
I have more money into my Barracuda than I'll ever be able to sell it for, but I don't care because I love the car and don't plan to sell... Let us know what you decide.