For anyone who isn't familiar with this type of cutter it uses a tungsten-carbide single point tool that machines out the seat at the appropriate angle. It behaves like a lathe tool – in reality creating a spiral cut. It's remarkably versatile in that DIY cutters can easily be made. Last year I rebuilt a Honda CB450 head and made up the required tool by brazing a tip to a piece of tool steel.
Unlike most cutters that only use a pilot to loctate a cutter head in the valve guide, this uses an additional outboard support clamped to the head for rigidity and precision. Any number of seat angles can be cut – I used a 3-angle cut on the Honda.
The question I have is that I would like a PDF copy of the original instruction manual that came with the set. Mine is missing and I know there are many setups illustrated for different applications. It's perhaps an early 60s Mk1 set in a wooden case.