The only reasons I can think of why they wouldn't work without milling .230" from the boss are- stud hitting the valve cover, the rocker hitting the guideplate or the guideplate not lining up correctly. Would any of these be an issue? Has someone done this before with no problems?
i had it done to a pair of E7's about 6 years ago. The guys shop is in my sig that did the job. He knows all those answers. Strength is the main reason you would want to do it....He used ARP on mine. give him a call his name is Jerry Chambers at the HEAD Shop. Or thumper 460 also does this from here on the board. Hes located in Florida. Either one can answer your questions
Jack
They are only mildly stronger than your fadtory set up, and the thing is you don't need a fancy valve train when running gt-40's cause its not like you are going to be making power up high. Save your money for some roller rockers.
(I am assuming you are not running a mechanical cam)
the factory studs are press in fit, they can pull out with moderately stonge valve springs, larger cams with any kind of rpms.........I'd do screw in's with larger studs.........
Jack
I'm going to use Scorpion roller rockers, but with pedestals it might be a pain adjusting the preload.
The cam is a Comp xe266 with .544/.555 lift. I'm sure it will have a reduced base with that lift. It might even have two different base circles the way they make cams these days. In 10,000 miles I'd rather adjust the rockers than add a shim when everything seats in.
The reason you mill the pedestals is so that you have room to adjust the rockers, so the rockers dont hit the studs, and so there is room for guideplates.
I have done it both ways. Currently, I am using Comp Cams retro stud kit, with 5/16 thread to fit the pedestals and 7/16 for the rocker adjustment. I used roller tip rail style rockers so I did not need guideplates.
You either need to look at a similar combo or mock yours up. You can always take it apart to mill if it does not work.
machine work to make room for guide plates and studs. no other option. otherwise wont work except than the retrofit that rd said. done it both ways also for customers.