I have run the plain jane small Dove rockers with up to 700 psi springs for many, many years with no breakage. I broke one pair, on one cylinder, back around '97 when I spit a head gasket and filled that hole with water.
Those same rockers were on my EMC motor at 759HP and 6500RPM. You had something else gone astray....
Should add that the same engine has a Scat cast crank - 4.25 stroke - and hit 672 for TQ....no holes in the pan yet...
