Macintosh System 6.0.8 running on an #AtariST 520STE with Spectre GCR! I don't yet have a working floppy cable, so these instructions were just what I needed to set up a bootable image on an SD card: http://obsolescenceguaranteed.blogspot.com/2013/04/atari-st-ultrasatan-spectre-mac.html
The instructions are for Ultrasatan but work fine with ACSI2SD.