I measured 22.75Kcd at 5M. (I know, I said 3M in the original post, not sure what I was thinking there… I always do 5M from the exact same location)
So the extrapolated 298.33M doesn’t quite match the stated measurements. This could easily be due to the fact that I used a 4.2V 18650 and they most likely tested with a pair of CR123 at 6V.