I did a manual check - 90 degrees at the bump stop on the shock but that wont be reached in action.
I have mocked up all the axle brackets but am still waiting for the new rear axle to tack them to so I started on the rearward structure (supporting the chute, push bar etc).
To get the main rearward central tube aligned I started by aligning the dummy axle as much as I could so I could take triangulated measurements from that but for the life of me I couldn't centre it, then realised the Watts linkage was mocked up.
At least I know it works.
I ended up with plumb lines, string lines and a laser level. I havent reverse measured it to the axle yet (fear of what I might find probably).