You can call motion pro and they will make you a cable, I am not sure about the thumb throttle. Or all terry cable. They have what you need and if you need something special they will make it for you (800) 854-4691.
I just called Terry cable because I need the same thing.. 37$ for the cable and he said like 124$ for the thumb throttle (assorted colors).. The cable works from a 32mm up to a 40mm larger carbs need a diff cable..
Well still couldn't get full throttle but come to find out the throttle box was holding up progress. Ended up taking the dremmel to it to lengthen the throw