I'm building the Hoglet and want to try an O ring head gasket. The O rings I have are 1/16" by 1.25", Viton. The question is how deep should the groove in the head be, how much crush? The rings are about.070" in thickness. On scrap a groove of about .045 seems about right. Or would the best idea be just use a traditional gasket and not risk the heads which already have a lot of work done?