my head's have not been milled andlluciano77 said:I have pretty high pressure valvesprings. I originally had ARP regular length studs. I kept breaking them. I switched to the studs that are designed for roller rockers, and haven't broken one since. They are approximately 1/4" longer. That will give you more thread.
Just make sure your valvetrain geometry is correct. With excessively milled heads, you may need different pushrods.