Sounds like the differences have more to do with the oil routing in the blocks than the rockers. Just because there is a difference in the casting number doesn't necessarily mean the rocker design itself is any different than another. I would call Patrick and see if he could shed any light on interchangeability issues you might face. Its possible if there is a specific rocker required for your application, and non-specific rocker could be modified by grinding a slot or drilling a hole to make it work fine.
