Put everything together. looks real nice. I was hoping the slop in the action would go away with everything cleaned and tightened up, but no luck. With the band tightened up, the action easily slides forward 1-2 mm - the force of the bolt closing is enough to push the receiver off the plate by 1mm, and pulling the trigger shifts it back.
So, the wood in the barrel bed is tired, and the band is not capturing the barrel into the wood. Nothing a business-card shim can't fix for now. I'll tune it up so it at least doesn't rattle and shift in my hands when I pull the trigger, then I'll be shooting it. Suppose I could sell the stock for a pretty penny and put new wood on it, and fund a few more projects, but let's not get ahead of ourselves.