As a quick reference, the Chevrolet Power Service Manual from 1988 states "Production Chevrolet small-block rocker arms have a nominal ratio of 1.5 :1." Another source book by David Lewis states " ROCKER ARM GEOMETRY Small-block Chevrolet rocker arms (part number 3974290) are of the ball-and-socket type. A 1.5:1 ratio isbuiltinto the rocker, and the rocker's stud ... In 1990, GM introduced a self-aligning rocker with built-in alignment rails at the rocker tip." I too have been around Chevy V-8 engines for more than 40 years. Built a few small blocks and many big blocks, worked as a speed shop manager from 1980 to 1985. Worked the parts counter at numerous jobber parts stores and managed an ACDelco store for 7yrs. I also have drag raced on and off since I was 16 yrs of age. NHRA tech in stock eliminator uses 1.5 ratio as the spec when checking lift at Natl events etc ... The common example many cite is .300 lobe lift X 1.5 rocker ratio = .450 lift.