Technical rocker jumped a valve - new melling pushrods bent 5 thou in center

So have a GM stock i4 151 cid, put a head on few months ago.. just had one rocker jump off 2 months back - motor doesnt see more that 4500 rpms ever, never seen this and set hundreds (if not thousands) of valves - my first time dealing with this.

fyi rocker ratio is 1.75 and the rockers are long slot type / they do not have the "Ears" for aligning the rocker tip onto the valve tip like sbc ones do -

Hydr lifters.. few old rods were VERY slightly bent, so ordered 8 new melling ones - checked them and they too are about 5 thou off in the centers??

Whats the tolerance and any ideas? Ill be checking coil bind - but these were the same springs from before and the motors 15 years old.. very odd. The screw in studs with integrated nut did not seat all the way and im wondering if the studs are perhaps low quality / flexing - they are not any different from the stock press in studs, but perhaps lower quality, it was an off brand head.. maybe ill put in a washer to snug the stud down more-

 

Dirty guides will stick the valves, and stuck valves allow pushrods to unseat and/or bend.