I took a different approach.(though, I like yours better). I trimmed away part of the cable housing that extends through the firewall. This gave the cable another inch or so of distance. I also added an extension to the throttle bracket on the carb so that the cable attched well forward of the original mounting spot. This took up the extra distance I gained in the cable. This gave me just enough motion to fully open the carb. BUT, my accelerator pedal is as high as my brake pedal!!!
I'm a hobbyist. Not a professional. Don't be hatin'!