I didn’t measure the offset, but the largest cog does extend beyond/farther in than the spider. I’d guess the cog thickness which is less than 2mm.
I’m glad it is working for you. It is just odd that it has been lost on so many mechanics over the years.
I probably won’t be convinced since over the span of 30 years a lot of freehub body swaps could have taken place. I know 7 speed freehub bodies have a cassette depth of around 31mm, and as you brought up Hyper-C loses about a mm of spline. Hard to do the math and fit everything into 126mm.
John