Edelbrock Cylinder Head Quality

Yep I got some last year , some of the plug holes needed re- tapping and rocker shaft threads were rough also, did not check anything else so Im wondering why i keep bending pushrods and only on one bank yes they could be slightly shorter which I have custom ordered , would any of the above issues cause the pushrods to bend
Maybe best for another thread....
- Springs used?
- Peak RPM's?
- Cam lift and type?
- Pushrod brand/model?
- Rocker ratio?
- Any checks for pushrods hitting guide holes on that side only?