Does what you want differ in any significant way from an already existing
Ampro LittleBoard, or Megatel Quark?
(small floppy controller with serial/parallel interface)
There have been numerous floppy drive form factor single board machines.
There was one that was marketed as an external "drive" for Apples, that
could "also run CP/M".
--
Grumpy Ol' Fred cisin at
xenosoft.com