Did a few two engine ferries in my 727 days. Boeing had a section in the FPPM with all the numbers. Max T/O weight came down to around 135k if I remember correctly. The crew had to have another box checked during training doing a two engine T/O with an engine failure. Captains already got a single engine landing every 6 months. We had to coordinate the departure with ATC. One time climbing out ATC asks which engine is inop “so they know which way to turn us.” I look over at the F/O. “Well tell him.” “It's number 2.”