That would be slighty over a 3 stop push, quite a lot, but I understand films like Provia 400X can handle that, I'm not sure about Ektachrome.

If I were you, I'd try taking one of the rolls to a pro lab and explain the situation, they might be more salvageable than you think. On the web, it seems a 2 stop push might be viable, and then you're only one stop under, which is not as bad as you might think.

Talk to a lab, and try push processing one of them, you might just get away with it. Good luck.