The pitman arm is dumb.
Grind the top lip away until the cap can be popped off:
Here's the insides:
Make a thing. Yes, the surface finish is that bad.
All the ugliness goes away when it gets pressed in:
....and welded. The hole is just a straight-through 9/16" for now, it will get tapered later for a tie rod end, or whatever ends up there.
Here it is back on the box. I initially tried a YJ pitman arm I have laying around, but the extra drop was a no-go, it hit the diff far too early. Even with this one, it will be a toss-up which will limit the uptravel first--the pitman arm, or the frame where the pinion yoke will hit.
Here's where the axle is sitting now. It's still a couple inches away from full bump here, but I need to make some sort of links between the truck and the axle before I go any further. Also, I'm thinking the leaf springs will probably give WAY too much lift in spring-over configuration. We'll see where the front ride height is able to end up before committing to an alternate idea. I can delete the overload leaf to drop it 1/2" to start with....