I use and recommend Harland Sharp Roller Rockers. They are made in the USA by a great family. I installed Harland Sharp Roller rockers on my stocker when US 131 switched to IHRA several years ago and roller rockers are legal in stock at IHRA. Roller rockers will not give you horsepower, they will give you durabilty. The last year US 131 was NHRA I entered a weekly bracket race with my stocker and was nearing the final rounds when a pushrod went through my NITRO Carb stock type rocker and that cost me several hundred dollars. I had three sets of the new NITRO rockers and happily sold them on
www.classracer.com when US 131 switched santioning bodies. I have the same set of Harland Sharp roller rockers today and they will be cheaper in the LONG run for many racers.
I just had HARLAND SHARP build a shaft rocker system for the car I want to take to Bonneville. They did a great job and you can see the Harland Sharp family at assorted races in the Midwest.
Phil