I'd like to know this too. I tried all IDs but it seems like only 7 works. I'd rather the pixel binned 16mp instead of the full 64mp sensor.
PS I had to set Back Camera 4 to "6" in order for slow motion to work with the 64mp camera. It's not proper slow mo though. Anybody know how to enable >= 120fps in gcam? Stock cam is good but slow mo doesn't have sound it seems where as in gcam it does.