You might find my Ethernet/IP module useful for this, without needing to buy it. Export the Logix 5000 project in L5X format. You can import that into an instance of my driver and it will render the data types and tags into my module’s virtual controller. OPC item syntax is identical to that in Ignition’s own Logix v21+ driver (with a handful of exceptions). For even more fidelity, do the above in another Ignition gateway, and let the first gateway connect to it with the normal v21 driver.
When ready to test with a real controller, just delete the virtual device and replace it with a v21 driver instance of the same name.