When the Red Rocket's 327 was rebuilt we chose these Comp Cams Magnum Roller Rockers to replace the stock stamped steel rockers. They fit under the stock aluminum valve covers (just) and feature a roller tip — they are not 'full' roller rockers. My engine builder was very happy with the way these rockers fitted, the roller tip sits right in the centre of the valve stem.
The stock stamped rockers are known to be very inconsistent, with the ratio of the rockers varying wildly. This article from Motor Trend found that the Magnum Roller Rockers deliver consistent lift and produce more power than stock rockers (around 5hp).