We are in process of doing a rust free 57 Dodge wagon with a 5.7 Hemi that went under water to the roof.

All the wiring is junk.
All of the electrical components are junk.
Any motor parts the have open bearings are junk (the water pump was locked up!)
All of the brake parts (4 wheel disc brake rotors are all pitted already).
All of the interior.
Rebuilt the trans.
Pull down the motor & clean it up.
Replaced the rear axle assembly.
Clean the fuel system (tank, pump, what was about 1/2 a tank it full to the top.)
Scrub and disinfect in inside and underside of the body, inside the doors, quarters, frame rails, probable will end up replacing the exhaust. Its amazing how many places dirt and debris got into.

This car was cleaned up by 2 washings, and the complete interior removal as soon as we could get it out of the water. Then we pulled all the plugs, drained the oil/water, WD40d the motor 3 times, flushed the motor with oil 3 times, and pulled the front sheet metal and cleaned everything again within a couple of days. Even after all that, there was still some surface rust on the cylinder walls after we pulled the heads. I can't imagine what it would have looked like had it been sitting for several weeks before we started the clean it up.

There is no way I would do this on a newer computer controlled car. Gene