BBC rockers on a Pontiac
 

I know there are a few guys who do that, CV1 heads are made for them also.
Crower has their 1.55 ratio Stainless Steel BBC rockers arms on sale for 249$. Normally 674$
About the best stud mount rocker you can get.

Length between stud to roller tip and stud to pushrod cup too long. A Crower 0.090 offset trunnion BBC with some short pushrods can work.

Why on earth would you want 1.55 ratio??

That ratio is probably a "break in rocker" reduced ratio so you do not have to remove springs for a flat tappet break in. They have 1.33 SBF ones that will work for our Pontiacs I've used on the 455 in my 78 TA.

I have yet to verify the ratio but i recently purchased a 455 that has a small ultradyne solid roller and the original owner swears 1.8 harland sharps rockers on it, under stock chrome valve covers too. when i bought it, I only pulled one rocker cover, as it was enough to know this was a well built /executed motor and the sharpes.
I was skeptical, about even the roller cam, until i snaked a camera down into the valley area. Pleasantly suprised.
Ill slide a dial indicator on them at some point. This motor would have been done in th early 2000s before we had access to many hi performance parts and rockers as we do now.