I agree with your initial thoughts, David. For that weight, the stencil was upside down (and there could well be others with the same "feature", but there are lots (many thousands, probably) with the regular CIIG. There are also differing forms of the CIIG letters over the years - such as with a space after the "C" and before the "G" and with the "II" being slightly smaller than the "C" and "G". Occasionaly, the CIIG is applied as script rather than stencilled.
Even if a weight had a clear base, it would not be normal to apply a an inscription of any form such that it should be read through the weight.