blown head gasket

i just bought on 1986 thinderbird with a v6 engine, the owner said that head gasket was blown, how can i tel if this is true?? the car starts and runs, no smoke from exhaust and no water in oil, he says that car over heats all the time and that is why he sold it. can anyone help? thanks

Could be as simple as a bad t-stat from what you described.