Chevrolet Repair: overheating, blown head gasket, radiator fluid

Question
I have a 1989 Z24. I have replaced the thermostat and heater coil and it is still overheating. Coolant is not leaking out except through the overflow valve. Other than this the car runs good. Also nothing coming from tail pipe. Fan is working. Have flushed out radiator. Does this sound like a blown head gasket?  

Answer
cehck the oil for traces of radiator fluid and vice versa. if yo find oil in the coolant or coolant in the oil, i would say yes, but it could be that the water pump could be to blame, if its not working right it will not circulate the fluid to cool the engine. check the fluid level and if its fine run car for a bit to get it warm and then find the hose from the radator to the engine and pinch it, it will be hot. you should feel a surge of coolant after you release the hose. if not then your water pump is not working. it a pulley run by that belt on the side if im thinking of the right year. anyhow go to a parts store and ak how much it is to buy a replacement or take it to your machanic. my water pump cost me about$80 plus  i got some back for bringing the old one in. prices may vary where you are.