The design exists, has been prototyped in 3D printed parts, and lacks a builder at present.
Recommend you contact
Robinson Industries (the owner usually answers the phone). You might say something along the lines of you're aware of excellent work performed for Triumph Rocket III owners, and you, like others, would *also* like to have additional parts for they sixth gear design he has seen.
When i spoke to him, he said he had another project he needed to finish, and discussed with me the few parts needed, and allowed as how he thought that would "not be difficult."
If enough of us call, maybe we will push the project over the edge to reality.