In my case, it's a sacrificial engine till the airframe is sorted out, at least. Then it's time to build one like I want it. I won't have needed to run it hard to seat the rings in an unproven airfarme. I'm still looking for the replacement engine to build so when it's time, it's a matter of swapping engines, not a major period of down time. At least that's the plan now, subject to change at any time.