Strick,
Have you checked the carburetor and ignition timing? If the fuel mixture is too lean or the timing too retarded, your engine will get hot. Also, can you feel if the upper radiator hose is getting hot? It should start heating up quickly after the thermostat opens up.
Just curious, did you check the CorvetteForum.com? There is a discussion about exactly your problem going on there, right now. Click here:
http://forums.corvetteforum.com/showthread.php?t=872892
Paul