That looks really good Oscully. It looks minimal and simple and is probably a better method than I have suggested in attached picture. I was wondering if it would not be even simpler to use the existing throttle lever because there are brackets above to attach cable barrels to etc and brackets above & below to attach springs to. Just a thought.
I also attach pics of Jimraysr's bike because he used this method.
I must admit, however, your method does look clean and simple Oscully.