Skipjacks, I have been in the process of moving, frustrating as bike tools and stand may not be where I am.
The GP2 “gripshift version” did not work with my SRAM gripshifter, not a big deal as I got them for $10. The gripshifter requires an interlocking grip. I ended up buying a second set of end bars, similar to the 3” endbars mentioned above. I figured putting those end bars outside my grips would put the grips at about 660 which is what I was trying to achieve, in terms of hand position.
The 3” end bars did not fit over the plastic clamp holders on the SRAM grips. I did a little testing and figured out the clamps on the end of the grips were not necessary so I sawed them off. I also took your suggestion and switched the position of the brakes and inner bars. I also wrapped the metal inner bars.