Rick, I got close to the right SAI with my new dimensions, mostly confirming their accuracy. It's a little less than 3.5 degrees but with a couple of shims it would be right on. Actually the SAI is variable, if you define it to the ground so maybe that's why they specify a range in the specs. Every reference I've seen for SAI shows it from "true vertical" not relative to the spindle.
I agree that it might be best to fix the lower a-arm, locate the upper balljoint at the 9.75" and 3.5" SAI, and then locate the upper a-arm pivot from there. That will eliminate any ambiguity regarding shims.
Here's where the SAI is shown as 3.5-4.5 degrees: http://chevy.oldcarmanualproject.com...esto/56031.htm