the Apogee Katana is a larger Zephyr 54 mm motor with ebay can be flown on motor ejection. if you only use the bottom fin section it is a Zephyr and your ready for l2.If Apogee is out of Zepher rockets, I wouldn’t wait for a restock. There are plenty of rockets that will work for you. If the quality of the instructions is important to you, take a look at a Binder Design Excel, a SBR Fusion or an Aerotech Sumo. The Sumo is basically a low and slow stubby rocket that goes together with CA glue. The other two use conventional construction techniques like epoxy (any you can find at a hardware store would do). The performance of the Excel or Fusion would be similar to the Zepher.