Most of Ford's FE castings had walls of at least .200", and it should be safe to remove .100" or so if you do it carefully. I use a small round stone when working around those bumps. The one you have to watch out for it the oil feed. Lots of folks used to remove the bump in the other ports, but found that they would leak oil unless you epoxy a stud in place for the rocker arms. I have flowed probably hundreds of FE heads, and I have found that those bumps don't really hurt flow if you just blend them gently. Don't remove the hump in the exhaust ports, that is a water passage. Joe-JDC