Got a hold to a mid-90's CR250 head that had a little damage done.  Kinda funny because the spark plug hole is not centered to the combustion chamber so I threw it on the face plate using stand offs and spun it gently.  
I cleaned as much of the squish area damage as I could without changing the head design significantly and then took down the mating surface to match.
		
		
	
	
		
	
		
	
		
	
				
			I cleaned as much of the squish area damage as I could without changing the head design significantly and then took down the mating surface to match.