Thanks for the update. Need this information out there for everyone to keep in mind. I knew there was some binding to worry about with the springs not being tall enough and the valves not being long enough for the longer springs needed.The .550 max.lift deal was on the smaller bore 348 cu.in. based engines.The "out of the box" maximum is .600. If you're running more than that,and/or a healthy mechanical roller cam,both the springs and valves must be changed.