400 stroker rookie

With the rockers removed lay the edge of a steel ruler (or similar) along the tops of the valve stems. Even if they're slightly different heights you'll be able to see if the tips are parallel to the straight edge. The same applies if you put the ruler in/along the bottom of rocker shaft recess in the head. If both checks look 'level' then the rocker arm pivot may be bored pissed.
Neil.