Roller rocker dims vs others (chevy, ford...)
 

I found a set of new (but old) aluminum roller rockers (black) with just a "1.5 USA" stamped near the tip, no other markings. How can I confirm they are for Pontiac and not for Chevy or Ford or …? Is there a dimension I can measure that would confirm if these are Pontiac or not?
Im looking for rockers that will be used on a mild 400 build with stock heads (46,16 or 7K3).
Thanks
Frank T