So how hot do you think you would have to get an Ohv to overheat to cause damage
You should be fine since you pulled over and shut off the engine.
Head gaskets are not damaged by heat directly, the damage to the gasket is from uneven metal expansion when coolant is not present.
Normally the block and head heat up and expand equally because of coolant circulation, the heat is generated by the 1,200+deg combustion temps, and it's then spread through out the cooling system by circulation(water pump).
If circulation is stopped the coolant closest to the combustion chambers(cylinders) can quickly get above it's boiling point and turn to vapor(steam).
The Vapor occupies more space than the liquid so pressure in the cooling system jumps up and rad cap opens to allow coolant in the rad to flow into the overflow tank, it can also pop off or split hoses, as coolant in the rad is sent to the overflow tank coolant level in the engine drops.
Gravity means the remaining coolant will be in the block and not as much in the head, the head metal expands unequally and can crack, but also expands against the block surface and head gasket, this causes a "rubbing" and over compression of the head gasket.
This uneven expansion can compress part of the head gaskets cylinder ring past it's recovery point.
A head gasket is compressed and uncompressed in daily operation, that's what it is there for, uneven over compression and "rubbing" is what leads to it's failure.
The 800+psi in the cylinder from a running engine can then breach the head gasket at an over compressed point(next to it actually), this is why its important to shut down the engine ASAP.
Once the 800+psi pressure has breached the gasket, it is officially "blown" and won't recover after cooling off.
Shutting off the engine immediately stops the heat source, but also stops the 800+psi that breaches the gasket.
As the engine starts to cool, assuming hoses are still intact, the coolant in the overflow tank will be pulled back into the engine.
There will be "air" pockets in the cooling system after overheating so system needs to be purged, same as refilling system after flushing.
There is a simple "glove test" to check for a blow head gasket.
When engine is cold remove rad cap and overflow hose.
Put a latex glove or plastic baggie over rad cap opening and seal it in place with a rubber band or ??
Start engine
If coolant starts to come out the overflow outlet when engine starts then you have a gasket or crack issue
If no coolant is coming out then place your finger over the overflow outlet, system is now sealed
If glove starts to inflate you have a leak from a combustion chamber(cylinder) into the cooling system, so either a blown head gasket or crackled head.
If glove doesn't inflate you are good to go.
A head gasket leak will blow up the glove instantly, so in less than a minute you will know.