I just went through this about a year or so ago. I ended up going with the Raylar rockers and the special nuts that come with his kit. I believe the rocker body itself is actually a comp cams unit.

The raylar rockers and nuts that come with them re-use the stock studs and are a non adjustable unit. any adjustment is done by changing the pushrod length (similar to an LS motor if you are familiar).

This is the only setup that I was sure would fit on the stock valve covers