You have to fit or adjust them all. It's important to be smarter than the cam button you chose, as any of them can be made to work if you are. Maybe it is important to chose the simplest and least expensive button to try first.
I make myself an aluminum button or use the cheap Comp nylon. I still end up machining the bolt heads too.
I like and use the expensive AREngineering timing cover the best of them all. However I've never tried his cam button with his cover. It may work great.
