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Anything is salvageable. I would start by drying it out completely.
Let it dry out completely before even trying to start it. Also, although it should be a closed system, I would also change the oil & filter before trying to start it. If it starts and runs with no electrical or other issues great. If it does have issues, it will depend on what they are and how much your friend wants to spend to try and repair them.
Another consideration is mold and other issues (smells) in/from the carpet and paddings. At a minimum, I would remove them, replace the padding and steam clean the carpet (or replace it as well). If the water got into the seat foam, I would also consider replacing it as well. IMO, beyond the potential mechanical & electrical issues, my biggest concerns would be the mold and other health issues that could arise from contaminated flood water; some can be highly toxic.
One of my friend took on some water it got under the seats and into the fuses on the passengers side, is it salvageable.
As others said, dry the electronics well before trying to start the car, and I would strongly suggest he replace all of the carpet, as well as the seat foam and the leather if the seats got wet as well. The flood waters are full of raw sewage and chemicals, and are considered toxic.
Man, sorry to say, there is going to be an awful lot of salvaged "parts cars" out there in the future. And, not just Corvettes. No discrimination here.