So here's a question as far as positioning; how have you been able to see the window and hold the timing light at the same time ...
It's done in steps, not all at once.
Shoot the timing light at the flywheel to see where you are then turn it off & set it aside.
Then tweak the distributor a little bit & tighten it, then grab the gun and shoot it again to see where you are.
Do one, then the other if doing them all together requires too many arms.