Those GM/LS1 type roller rockers came with my 2002 vortecs...I believe they were new that year. FWIW I had my headwork at Flow Tech, which is a very reputible shop, and they recommended keeping the factory roller rockers. I did and they work great for me. Since they sit in a cradle there is no rocker weight to support vs a standard rocker setup....much less VT weight.
But if you want to go to a standard...ARP makes a stud kit for those heads that screw in and accept a stock or after market roller rocker.
John