The timing ball and pointer above the starter can be used for ignition timing using either #1 or #6 cylinder as the reference point. If you want to use the hole on the driver's side, you would have to pick another cylinder, I suppose, or make a different mark. If you align the ball and the pointer above the starter, then use a home-brewed pointer and a painted line, you could still use #1 as the trigger cylinder. It would just have two different places to check in that situation.
The reason either #1 or #6 work for timing, both pistons come to the top of their stroke at the same time. If you use #6 plug as the trigger, the ball just lines up 360 degrees (1 full turn) away from the #1 firing point.
Jerry
