The valvetrain is complicated.. and it's similar to balancing the rotating assembly in that it has to deal with harmonics that are a natural part of it's operation. Bent pushrods can be from a bunch of things. Some possibilities: Mechanical contact... retainers to rocker, pushrod to head/gasket/guideplate, valve to piston, coil bind on the springs, loss of lifter plunger motion, guides too tight. Deflection of the pushrod itself. Harmonic issues from wrong springs, pushrod angles, rpm, or poor geometry. So there's no "it's always 'x'" here. If you are not sure, I would have someone who is sharp look at what you have, or post a bunch of pics of things like the threads left showing on the adjuster, the sweep pattern of a few cylinders, a side close up view of the rocker with the lifter on the cam base circle...
On the Edelbrock heads... They use a helicoil in the rocker support, but you want to make sure the bolts thread completely through it. I've found factory bolts are usually too short, so I replace them with simple grade 8s of the same diameter that are 3/8" longer. IIRC the rocker shaft torque spec is 20ftlbs. It's not too much.