I have the small block Indy-Brock heads on my Dart, Which were set up with Indy's big block rockers (shafts are moved up and back). The cam that was installed at the time is a Bullet roller with .668 lift In/Ex with springs set at 195# on the seat and 580# over the nose, the Indy rockers lasted just over a season and a half before they started snapping off under the spring side of the rockers.
I bought a set of Hughes big block rockers in 2010 and put stiffer springs on the heads 250# on the seat and 625# over the nose, no problems with them for 12 years now. So I will give Hughes rockers an A+ for strength and durability, and I have also gone as long as 3 seasons without having to relash the valves with them.
