The magnum rocker bolts are 5/16-18.
To use a Chevy rocker, I used a conversion stud from ARP. It’s 5/16-18 on one end and 3/8-16 on the other. Hughes engines sells em. View attachment 1716207489
Those are a nice kit. Crane used to offer a similar kit that included guide plates too. Even still though with the Hughes or Crane kits, you still have a 5/16 stud holding everything to the head.
