Well, I showed it without the guide/indicator (now pictured with the magnet that holds it to a head bolt). I'm a little uncomfortable with bumping the piston up against a stop. Not sure I could do it gently enough when turning over the engine with the rear wheel. I think of the stick as a vernier that moves with the piston and is accurate to about 1/64". I don't have a timing disk, but even if I did, I'd rather not open the primary just to set timing. It's bad enough that the timing cover has to come off. (Insert Orabanda's picture of magneto flange slots here.) I suppose you don't like to remove the timing cover either, which, I also suppose, is why you made the device. I have kinda settled on 11/32" as the target, but like the idea of trying other values if I want. That would be a bit tricky with red Loctite (unless you made a set, of course).
This should, appropriately, be followed by "I'm probably wrong."
Richard L.