I actually watched that video earlier today. The issue has nothing to do with throttle length, bracket placement or linkage. It's a problem with the relationship between pedal and carburetor throttle geometry. Basically, the pedal doesn't pull the cable far enough to achieve WOT. The accelerator pedal will bottom out on floor before the primaries are totally open.
First, welcome to the site !!!!! 2nd, you may need to find a spot to hook the cable a little closer to the shaft for more action. Be sure 90% of your slack is out of the cable between the carb and cable bracket.
