Airbubba
Wouldn't an ETOPS/EROPS plane need some sort of flight test before taking it over water? Or, could the test be done on the trip to ZRH with the ferry crew and the next leg could be a revenue sector?
Every circumstance is different I guess but I do know if we've had an straightforward engine change on our ETOPS type the "check" basically involves getting airborne and can be considered done if all is OK before entering the ETOPS segment of the route (if there is one) , then a quick write up in the tech log and a suitable message is ACARS'd to base...that is it.
I've done a handful post engine change and there's nothing Yeageresque about the check, no slam checks/ engine acceleration checks or anything, it's basically a question of does the engine work ok for takeoff, climb and initial cruise, so FWIW though probably not relevant in this case it can and often is done on a revenue sector immediately after an engine change.