Seems fine. Just use the quality outlets mentioned elsewhere here. Not Leviton. Personally, I'd put some thought into the exact placement of the receptacles, so that if you wanted to swap directly to a Wall Connector in the future, it would be exactly where you would want it, and there are sufficient clearances for the Wall Connector in all directions, it's at the right height, etc. I wish I had done that with my 14-50 - as it was I had to cap the old junction box and route Romex to a slightly lower, slightly offset, different location for the Wall Connector.
Also make sure there is sufficient extra wire length to connect to the Wall Connector. I have no idea whether extra wire is to code (nor do I care), but I would not hesitate to leave an extra 6-8 inches of slack (or a bit more if possible) in the run.