Stock magnum max lift

From what I understand and may or may not be true. The hughes engines upgrade from the r/t cam is around .533 lift maybe closer to .540 the problem is the retainer to guide clearance but the hughes locks and retainers provide the clearance. Probably the entire spring, retainer and lock kit from hughes would work. The 380hp crate motor ran .513 lift with nothing but a spring change on stock magnum heads