I'd connect the a500+ floppy drive to escom A1200. just take care of the READY signal.
IIRC, escom ignores it, so it should be easier than other way round.
If it has the same symptoms, at least CIA chips are ok.
then you can run X-copy on A1200 to test drive.
recalibrating is fiddly, but not too hard, I've done it by hand.