Don't forget the timer.
Heading, timer, and cross hairs. Analog bombing computer.
Now if Hitech would put up partial overcast over every field and lower alt cross winds to scatter bomb salvos. As is, a clear vinyl sheet over your monitor with a grid, your compass, and a timer. And salvos that drop in a predictable straight line. You would need to make several overlays for different altitudes but, I suspect your speed will be the same on every run. I'm not sure what the ring width scale\alt\speed is in the below photo. It's a good place to start. The AAF has manuals with the bomb type travel distance @speed, @alt. Similar triangles will give you the ring widths for your alts. But, since you have a bomb run calibration mode to take the place of all that. I can only see one other reason for this. Ad hock direction changes to out wit CV drivers without having to calibrate.