[Raptor]

There are a few companies that make some pretty slick ones that load the keepers for you and catch them when they come off, not a bad option. If you even consider doing this with the head on, block off the return holes with a rag or something to keep them from going all the way to your oil pan, it does happen. Another thing, you might want to make sure you are taking the springs off the cylinder the compressed air is on. I have seen that one happen as well (not me) once that valve goes down the little hole, your not getting it back without taking off the head. (they tried, I laughed)