And there we have the answer to the extensive rust. I'm willing to bet there is more we can't see.
If it could be verified as an original BB, it would, probably, be worth restoring, but to me, the hood looks more white than faded green. Not sure it's original to the car.
Yep, need lots more pics and info to decide what it was. Casting date and assembly code off the rear axle would be a good start.