Yeah, that is the plan, then fit it on the frame and check if things are looking square and the tail stock is moving ok before final welds. As for the shims to give the tail stock lock clearance, I may just end up notching out the support on the far end to make things easier after looking at it again.
Tonight I started with cutting out a notch in the tail stock support end of the rotary rail supports to allow clearance for the locking mechanism of the tail stock. This was later filled with a piece of angle tacked into place to keep the saw dust out. I'll be capping the sides of the supports using plastic tubing caps, same for the ends of the rails.
Next was fabricating a rear mounting bracket for the head stock.
Last up was drilling the rest of the head stock mounting holes and drilling and tapping holes for the stepper motor mount/adjustment studs.
The adjustment studs are about 3" long, so will be able to get all of the slack out of the belt once I get the stepper mounted to its bracket and the rotary frame painted up, which are tomorrows tasks. I'll be 3d printing a cover for the belt and pulley btw.
I was thinking the same thing when you first posted pics of that chuck. Doesn't need to be fancy, but self-centering would be a big timesaver. Grizzly and Penn State both have budget chucks that'd probably fit the bill.