OVERHEATING

So many hands have been on it I can only speculate. 1. was the engine block inspected and tested to confirm it had NO fractures? 2. Did the car operate at the correct temperature at anytime after the cylinder heads were machined and it was built up? 3. was it checked for leaks or leaking with a dye agent once again checking for a cracked block 4. Its possible an incorrect gasket was used(blocking) flow or debris found its way into a coolant passage in the engine restricting the flow of coolant internally I've seen it. 5. All engine sensors are function correctly,example its been scanned for DTC codes there are none? (Timing not so out spec to cause the issue) 6. Its been tested with a gas analyzer to confirm that there are NO combustion by-products in the coolant system. If the vehicle came to me I would diagnose as described. Regards

yes,after the car ran fine except the check engine lite came on and was advised by the shop that did the head gasket that it needed a knock sensor but it was o.k. to drive as is ($580 to replace it)

Being unable to check it directly, I can only make a few educated "guesses" now the functioning of cooling fan(s) I would also scan the vehicle again for codes even if there's no check engine light on the computer stores information in a freeze frame mode to capture Data about "events" kind of like a clue or arrow pointing a way.