not possible as far as I know. Those guns that do have ambi selectors have weird devices that pass through or around the gearbox to access the physical plate that does the fire selecting. All this is located on the left face of the gearbox on a v2 and v3. The mechanics are build on the left side of the gears and gearbox. As a lefty shooter you're either going to have to get used to the selectors being right friendly or pick a gun that is ambi friendly, which will expand your search to outside bullpup designs.
Choices are pretty limited... some mp5s, scar, g36, I think the masada, kac-pdw.
I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.