I am losing about a pint of water every time I use the car. I am wondering if as the car reaches temp, about 205 if the water is weeping out of the overflow tank.
Do they make a closed recovery tank system. ?? without a run off hose.

You can buy universal kits at a car supply store but it may be difficult to install it considering the lack of room under a Vette hood. The universal ones tend to have a squarish reservoir...not much room to install that shape. If you do find one, make sure you have the proper radiator cap...one made for a closed system. You can always buy a reproduction system from Corvette Central, Eckler's, etc., made for your C3.

You should first determine what, if any problem you may have with the car that's causing the system to vomit the way it is. There could be a bad thermostat, partially plugged radiator, bad radiator cap, etc. Make sure there is no other problem...you may end up treating the symptoms, not curing the illness.