I also modified the throttle tube to allow for the extra travel required when using a SHA15. Lengthened the slot 2.5mm with a Dremel carbide bit and not the stone bit shown. Deburred everything and tested operation. If I had gone any more, I think the cable slider would have popped out of the throttle housing. Installed everything on the bars and tested operation again, seems smooth. I used dry graphite to lube all the throttle parts.
So, left and right handlebar controls are finished now and a new set of repro Motobecane grips installed as these were the only ones I could find with a 4" inside depth.
On to the engine next.