I've been looking online but can't really find an answer for this particular thing.

On the panheads from s&s that have the shovel bolt pattern and they use on their P-series engines, apparantly panhead rockers can not be installed and you have to get this cradle of theirs for their roller rockers.
But the question is, are these just regular shovelhead roller rockers or something specific for these heads only?

As I said I've been searching for the answer, but not alot of info on it.

I'm trying to figure out if using their heads on a big bore motor I'm putting together makes sense or if I should go another route.
Btw, are STD still up and running?