That's what I was looking for, thanks! Custom Ore Generation includes its own RNG, and I include the assumption of averages in my calculations when creating the configurations (and there are options for uniform and non-uniform distributions) by halving the max and supplying the resulting value to both the average and the range.
One question: Those veins per chunk value; are they averages or maximums? If those are averages, what are their maximums? UPDATE: Never mind; I got this viewer figured out.
And trust me, I had enough of a nightmare trying to figure my way through decompiled vanilla; Java is not something I have much knowledge of.