Of course, the bet thing to do is to not lay up the car for winter.
But, if you absolutely have to, then the general concensus seesm to be that its best to fill the tank and, idealy put in a bottle of fuel stabiliser, suppliers like Millers do them. Add the stabiliser when teh tank is almost empty, run the car to get it into the fuel lines etc, then fill the tank. Do not use E10 fuel in any event, but definately not in an older Corvette and not for storing. If you do have to use E10, add some Ethenol protection.
The absolute best way to lay up a car is apparently to drain out the entire fuel system and refil with pure 100 octane racing fuel (VP Fuels), but I suspect that is a tad pricey for us "ordinary" folk!