I can't get around how the factory calculated the total gear ratio in the notebook(s) and need someone to explain that to me.

Let's take the notebook from -29 as an example. It gives 4.36:1 (another spec. gives 4.98:1)

Solo standard gearing was 21 cogs on the front sprocket and 36 cogs on the rear. 36/21 gives a ratio of 1.714. The front sprocket rotates 1.71 times when the wheel rotate 1 turn. The gearbox is locked on high 1:1. The transmission gearing is 84 cogs on the clutch and 33 cogs on the motor gear. The intermediate gear (36) does not matter for the gear ratio. 84/33=2.54 so when the clutch rotates 1 turn the motor rotates 2.54 turns.

So the rear wheel turns 1 time, the  front sprocket rot. 1,714 turns and the clutch rot. 1.714 turns. The motor gear rot. 1.714 x 2.54 = 4.35 turns.

So what I get is the third gear ratio 4.35:1

With the early Scout clutch gearing of 77/30 the calc gets a little closer to the notebook data on the final gear with 1.714 x 2.56 = 4.39
 

But then it goes wrong somewhere, the book gives 6.86 and 10.78 for second and first gear? In the gearbox where the slider is 14 and 18 and the sprocket gear is 22 ( the cluster gear does not matter in the calc. but the cogs are 22-18-14) Third gear is 1:1 second gear is 22/18=1.222 and first gear is 22/14=1.571

Second gear 1.714 x 1.222 x 2.54 = 5.32
First gear 1.714 x 1.571 x 2.54 = 6.84