The idea is to make a small single-board computer with
a microcontroller,
a WD2793 or similar floppy disk controller, enough memory to buffer a
few tracks, and a high-speed serial port for communication with the PC.
The board would have connectors for 5.25"/3" drives and 8" drives, and
would properly interface to all drive types.
Remeber that the WD chips are not still being made (are they?).
I've thought about something similar. A single-board computer with a raw
bitstream reader/writer (similar to a catweasel board, but not
proprietary). Save the data on a CF card or similar (there's rather too
much to send over an RS232 link in a sane time, and it would seem to be
easier to interface a CF card to a classic computer than to add a USB
port to a classic computer (this is important to me as I only have
classic computers).
-tony