I’ll join others and suggest perhaps an OM – it’s close in dimensions to your 522, with a slightly larger and deeper upper bout (see link to dimension comparison below) and a 14-fret neck. Neck shapes, nut width, scale length, and string spacing are endlessly variable because so much of SCGC’s output is custom, so chances are good you can either find what you want or have SCGC make it.
The OM as realized by SCGC definitely does have nice rich bass and lots of sustain. It’s a reasonable size and extraordinarily versatile – mine has been my go-to instrument for (gulp) twenty years now, and it’s not slowing down. And the 14-fret neck does offer a bit more real estate free of the body.
Link to comparison of OM-and-similar small-body dimensions on Google Drive: https://docs.google.com/spreadsheets/d/1hyOlL73qKs7LB6vIvvhZk4zYMhFSQdU99RN319ZGnrY/edit?usp=sharing
(ps if anyone wants to add a set of dimensions to that list, send them and I’ll add them and add attribution).
That said, if you like the 12-fret, a 00 or 000 12-fret would work. I’m fond of the sound of the SCGC o0 more or less across the board, and have a custom 00-29 (all mahogany) that’s quite extraordinary.