Corona running hot

I have a 1974 Toyota Corona with 117 thousand miles on it. It is a 2.0L straight four, manual transmission. It is running hot, and leaking oil. The radiator is not even close to full but the overflow tank for the antifreeze is more than full. I assume this is why it's running hot. I can't find any blockage in the hoses. If you could give any suggestions on why this may be that would be appreciated. Thanks alot.

David