Pat Mccarthy,I know machine shops do that but what would I use to cut the lower step on the guide boss? While on the subject I have to ask another question.What function does the lower part of the retainer serve? I can understand that it may add strength but it doesn't come in contact with the locks,my locks are.175 up the valve and with the locks and retainer sloped(angled) down,there is no way the locks will go there,if locks break or give way they go out the top(unless the retainer would break). Of course there is the off-set locks that will give you .050 retainer clearance I could use or shorter retainers.