After having the shaft in the freezer and the housing in the oven for a while they slipped together quite smoothly. The upper bearing, on the other hand took some convincing to get into place. In this photo it's about half way down to it's final destination but after a while I got it all the way down.
At first the spindle turned very easily but after mounting the lower flange, introducing the preload, it's a bit harder to turn but it's still really smooth. I left the seal out for now.
Then I assembled the drawbar and mounted the belleville washers for as little force as possible and did a crude test. I had to push quite hard to get the drawbar down enough for the pullstud to "click" in - it actually seems as if this is going to work.

Next task is to cut off the pneumatic cylinders and fabricate four standoffs so it can be mounted. Then I will make more tests with increased spring force.