Can it be rebuilt (with a lot of work)
?
No it can't. That car is DEAD.
There are many parts that can be saved.
The tail light brackets will be ok. On the engine, the generator pulley, the spark plug wire tube, the dist to carb vacuum line, the pump to carb fuel line, the whole bottom end of the engine will be ok, providing water didn't fill the engine. possibly the heads are ok. I bet the transmission was unscathed. Same for the front beam. Pedals, shifter, e-brake, rear seat crossmember, steering column should be reuseable.