No big drama . Just remove the inlet and exhaust manifolds, then rotate the engine manually and check for any water, if any water comes out , then drain the crankcase (sump), then use some water repellent to get rid of any moisture inside the cylinders. If no water found inside the engine, replace all electronic stuff, check/dry/replace all electric stuff as required, put a new battery. (After a big flood like this you will find the radiator is full of water too. But I am not smart enough to tell you a solution for that.) Drain the gearbox, diff, and look for water. take all upholstery seats consoles and floor carpets, either dry them or replace them, and you now have a car as good as new. But the easier and cheaper way is to buy a new car.