Since you are not running the stock/OEM carb (Mikuni TM38) I do not think the stock cable will work as the free length requirement is most likely different between the 2 carbs.
Get your desired thumb throttle, stock will work with that carb, then call Motion pro, tell them your bike, throttle, carb and they'll have a cable that'll work. Should be around $20-$30
P.S. please hit the "preview" button before posting to make sure your posts say what you want them to and are in the correct section.
Thanks and welcome to the site.