I've spoken with THT and they've mostly confirmed that 1,2, and 4 would be feasible to make. I'm pretty sure Ro 25-6981 is the one to go with until we know what the structure of NRX is. Any other interesting candidates I haven't mentioned? Not sure if there would be issues with legality for producing Hydroxynorketamine, nor how long would the effects last.
Personally, I'd love to see ISX-9 and Ro 25-6981, the most. Thoughts?