Many heads have the intake port ported enough to go through the wall on the pushrod side enough that the engine builder has to use a tube, half or quarter of the tube, epoxied into the head for the pushrod to clear using a offset intake rocker arm and a offset roller lifter cup moving the pushrod over to clear the new intake port.
Not for the faint hearted or novice unless their willing to take the time, money and effort to do that type of modification properly to work correctly