Ten degrees??? The definition of "non-interference" is when the valves and pistons clear each other even if the angle is 90 or 180 degrees. The pistons have to be able to make a full revolution while a cam is holding the valve all the way down.
And by the way, there are no millionth-of-an-inch tolerances in a car engine. Maybe a ten thousandth or twenty thousandth, on for instance the sides of the valve tappets (which you will notice are the smoothest and shiniest surfaces in your engine).
