whoa! thats a whole lot of theory right there. i guess i just wanted to know if there would be any benefit to have the plug vertical in the head. i noticed cr500 have there's angled back towards the intake side. anywho, thanks for the info!

Sorry for such a long answer.  This could also be added to my above response.

Manufacturing the dome so the the spark plug is in the center of the combustion chamber is desirable.   It also simplifies machining and reduces manufacturing cost.