I want to fit a riser block to my new Chester 626 mill, which seems to be a popular improvement. I have downloaded drawings from the Yahoo! group & studied photographs, but have a couple of questions. Why is the block bored out which seems to be extra work? Why mill out slots for nuts when the block could be drilled for high tensile studs? Can I use a 4” riser without replacing the z axis screw providing I move the cap head stop on the column higher?