Okay, I over heated my 87 daytona a few times and the problem never was a head gasket. In fact I never did have to do a head gasket in that car even after really overheating it a few times. Turns out the problem was a plugged heater core. For some reason on these cars, once the heater core plugs, the motor overheats. More so it's noticeable because the temp gauge swings back and forth a lot, where when the cooling system is functioning properly the needle doesn't move once you get up to operating temp. Not wanting to have to change the heater core, I gave the entire cooling system a good flush, then spent some time flushing the heater core. Then refilled the entire cooling system with distilled water/coolant, blurped the cooling system and guess what? No more overheating. All the head gasket changes in the world wouldn't have fixed that problem for me.