its from it hitting the head casting flash near the inboard (towards rocker fulcrum) side of the pushrod hole.

seen it plenty of times.
pull off the head and grind the casting parting lines/flash in those area's

its sorta hit or miss...most times there's clearance, sometimes there isn't. it doesn't help that improper securing procedure of the rocker stands could contribute to the rockers being offset and making it worse/better