Holley Strip Dominator vs. Edelbrock Victor 340

The pic of broken rockers in post #106 is an inherent problem, I believe, in the SBM. The rocker is too short, part of the original design, but nothing wrong with for it's original purpose. When you start using really stiff springs, you are ok with steel rockers because of the superior strength of steel [ over alum ]. With alum rockers, there is not a lot of section for the wrap around/metal thickness under the shaft; a highly concentrated stress area.
There was another thread on here a few days back about bushing alum rockers. I hope the OP is reading this because post #106 is a veeeeeeery good reason why you should not do this; you weaken an already weakened section of the rocker.