How Much Lift Can New Hemi Cast Iron Heads Take?

Does anyone know what part number the springs are in the new Mopar assembled cast iron Hemi heads?

I want to know how lift/duration cam I can run with them.

Also are they set up to run unleaded gas?

Thanks.

On factory heads they usally put the double .620 lift max flat tappet springs. You need to worry more about piston to valve clearance. They have been putting hardened seats in the steel heads as well. I would pull a spring off to check and be sure. Good luck, poppaj