273 rocker arms

interesting article on Hughes website...
"...Once the stamping technology developed to such a point that stamped rockers could be made, about the mid-60s, the more costly iron rockers virtually disappeared. They had somewhat of a resurgence when offered by the O.E.M. manufacturers from the mid-60s to the early 70s. They were a quick solution for the solid lifter or high performance hydraulic cammed engines needing adjustability. The valve spring diameters, pressures, valve lift, rates-of-lift, and RPMs today are much more aggressive than they were 40 or 50 years ago, and, therefore, we consider the forged iron rockers unsuitable in todays engines. At one time we sold them but there were so many problems with galling that we dropped them. They have the same galling problems as the unbushed stainless steel rockers..."