The springs in the assembly add an additional amount of difficulty - for instance the carb I used had a much stronger internal retun spring than the original teapot. Also the distance from the throttle rod attachment point to the butterfly pivot was different as well (different travel distance).
You start out by getting the carb idle set - then install the 1/4 inch dia linkage locking rod (I used a phillips screw driver) - and then adjust both the throttle rod - and the pedal height.
This second picture shows the trouble that may develop when the "throw" of the throttle rod doesn't match the teapot - and I also had trouble with rapid reelease of the foot pedal causing the linkage to "overtravel" back on the rebound. That is the reason for finding a place for a positive stop on the back of the engine. I used a stack of washers and a capscrew into one of the tapped holes on the back of the block - the return spring seats the inner end of the bellcrank against the washers and sets the pedal height.