Probably not of direct help to you, but of general note, to quote Bacon:
"Magnetos had a set of standards from their early days when they were always mounted on a platform. This set the spindle height at 35mm (code letter M) or 45mm (code letter K) above the platform, along with other outline dimensions. Over the years, magneto performance went up and their size went down, but the spindle heights stayed the same."