I think the industry term for this is called staking. It's usually used on nuts on axles or transmissions to prevent loosening through rotation, but it works to keep things captive as well. So maybe they didn't increase the press fit and just made it captive instead. So who cares if the actual press fit stops working, those staking distortions will prevent it from falling or rotating.Anyway, I wanted just to put eyes on these (I'm a very visual person) and did a search for "4.7l head removal" There is a boobtube video a guy made with about 4 different episodes. something interesting I noticed is that the 'owner' decided to go with rebuilt heads. In the last video, it shows him unpacking them, and you can clearly see divits all the way around each of the valve seats. The man says in the video that the place he ordered them from told him they were 'bulletproof'. In another video I found searching for "dropped valve seat" a guy takes apart a I guess maybe a 15 HP air cooled 4 stroke from a yard machine. It in fact has a dropped valve seats which he procedes to reinstall after cleaning up the head with a dremel, and subsequently uses a center punch to run divits all the way around the valve seats on the aluminum head. I suppose in effect pushing the metal tighter in. It looks horribly unprofessional... I suppose its not important.