Found the right adjustment screw on the INSIDE of the steering box towards the engine, and got the steering tightened up. I don't know how much I tightened because I had to work the nut up and down on the screw to get it to move in. On the test drive I could feel the other slop in the system now that the box is tightened up. A project for another day.
The radiator had sucked some fluid out of the overflow last night so that's a good sign. I did another heat cycle and burp with a little more angle. The temp stayed lower than yesterday, and bubbles were harder to get out. The wife helped me bounce on the bumper and popped some more big bubbles. I think I'm calling it good for now. Ready for another highway test.