I received the J1772 inlet and vehicle-side control board today!
I performed a benchtop test with a J1772 charging station, but haven't attached the charger yet. Once connected to the new inlet and control board, the charging station went through the self-test just fine. After a few seconds 240v was available at the charger connection. Success! Next step is to decide where exactly to install the J1772 inlet, and wire it up to the charger.