Try Hard-The angle of the upper A-arm does change but only a very small amount. Maybe this is the .001 Jason is talking about. It mostly changes in length when you use the tie rod to adjust camber.
I will repeat this here
"The instant center on this inverted strut (inverted McPherson Strut) is determined by extending a line at right angles to the kingpin at the lower pivot. A second line is extended on the upper A-arm axis. Where the two meet is the instant center. A line from the tires contact patch to the instant center meets the roll center at the vertical center line of the car."
You should be able to draw your own roll center sketch using the above procedure.
I drew one more sketch. This is a roll center diagram for the Oval car which has different camber on left and right. The left side is + 2 degree, The right side is -3 degrees. We are looking at a front view so the sides are reversed.
When you get the roll center on a car with front suspension assymetry you have to do an additional step. You have to get the instant center of the second side now. Where the two lines from the tires cross is the roll center.
Note the roll center is off to the left of the car (right on the sketch). It is also at chassis height when I would prefer it to be at road height. The camber on the left side tire has moved the roll center upward about 5 mm
Note also that I have labeled symmetrical roll centers on the diagram(What if both sides have the same camber). There is over an inch difference between the two one at -3 camber and one at +2 camber. I have called this a little defect and will do so again. You can adjust around it by tilting the A-arms once your cambers are set. There are other problems with this spring on kingpin suspension, mainly huge stiction, that could be eliminated with a more modern race car suspension.
I have written a spreadsheet that will calculate roll centers for twin A-arm cars. Link below. I also have discussions of roll center and nicer diagrams on twin A-arm roll centers on the TC5 tips and tricks thread.
The program below calculates roll center based on a few easy measurements of the car. For dual A-arms only.
A clever enthusiast could modify it to do McPherson Strut.
There is a better copy of this sketch on my next post.