Thanks very much for the info and for the link to the thread. I'll try editing the config files this weekend for 240p output and hopefully we'll have a GUI choice of resolutions in future revisions.
Thank you for your response! Sounds like recalbox won't get 3D iso support until the official build of Kodi 17 is ready, which won't be for a few months. Oh well, until then, I'll just swap between two MicroSD cards, based on which OS I want.