You have to keep the distance from the pivot point to the attaching point on the lever in mind as well. Bearing in mind that the attaching point may need to be indexed somewhere other than at 0 degrees either +/- of 12 o'clock to accomplish the desired relative cable action/position, taking reference observations and simple measurements can, in effect, take the place of complicated math.
On my rat, the swing starts at between 4 and 5 o'clock and swings to between 7 and 8 o'clock. The distance the TV cable travels is about a third of the distance that the throttle cable travels. These measurements are transferable.
The TV cable and throttle valve aren't THAT sensitive. The cable housing allows for minor adjustments. A click or two in one direction or the other will not jeopardize the life of the transmission so long as the setting is within nominal parameters and that one or two clicks can make sizable differences in performance and drivability.
