Very nice old bike. One doesn't see many from that era, let alone all original. Check out the serial number here as to how it falls in the time line.
Frejus serial number chart

It does look to be in very nice condition. What it's worth depends, of course, on finding the right buyer. In Europe, presumably.
Just a rough guess on my part, but I would say 1500 to $2000.

By the way, if you happen to work on it at all, don't throw ANYTHING away. Not even the original brake cable housings, etc.
Great old Frejus. Those pics of his grandfather are fantastic!