Be very careful when purchasing roller rockers for your Cleveland head engine. I don't know if it's still the situation today, but most roller rockers supplied in the past were actually for a Big Block Chevy. Fairly close ratio, but geometry is wrong. The push rod seat or cup is usually at the wrong angle for a Cleveland, and the roller tip is not optimized either. The Yella Terras mentioned above make a Cleveland correct rocker arm, but even they use the same rocker for BBC in their budget series. Do your research carefully.