<VV> Overheating

[David George]

Hi all. New to the list and have a question about overheating. Just purchased a 65 Monza 110 convertible and while it runs great right out of the gate, it starts pinging badly after about 20 miles of roadtime and then the temp/press light comes on. The car is heating right up and the oil on the dipstick is very hot after driving a while. All my shrouds appear to be in place, the bellows doors are opening and letting hot air escape, and plenty of air comes through the oil cooler (though very hot). I also took a peek down inside the fan to see if any critters had made a home there or if anything was caught in the fan area. Nothing. I have not take the fan shroud off completely since I am a little nervous to do so. Any ideas what might be causing my problem? The only things I have done to the car so far are to change the oil and replace the spark plugs, which were pretty fouled. In any event, the pinging and the overheating definitely appear related. Once that pinging starts, i know it won't be long before the red light comes on. Any and all help would be appreciated. 

Thanks to everyone in advance!

Dave